M-22 in "73" -? and Vent grilles Chrome in "73" -?

[James B.]

Maybe a stupid set of Questions, but here it goes - and let me know if this has been covered in the past and I will try to find it.

I recently picked up a manual called "New Product Information" - "Chevrolet 1973" (NPI-1-73), I'm sure I am not the first to ever see it. "This booklet highlights the 1973 product features that differ from the previous model year." It goes on to say...."All information, illustrations, and specifications in this booklet are based on the latest data available at the time of publication approval." By the NPI-1-73 am I to assume this was an early 1973 publication?


Question #1: M22 in 1973 ?

Pg. 116 of the NPI-1-73, lists available Manual Transmissions and only shows three options: 1. M20 3.11/2.54, 2. M20 2.52, and 3. M21 2.20. There is no M22 listed as base or as an option in 1973 for any vehicles. Now I have seen people online suggesting they have a 1973 Corvette with an M22 "Rock Crusher", Am I correct in assuming they are either wrong, mis-informed, or that they have a non original transmission? The NCRS TIM & JG that I have, dated (1999), on pg. 22 refers to an M22, Am I correct that this was included to insure no confusion regarding the aluminum case only or is it because there are cars with documented M22's in them from 1973? Also the next portion of the NCRS TIM & JG (1999) suggests that the second digit from the left in the Muncie 4-speed identifier should be (0,1, or 2). Does this mean that there should not be a "3" for 1973 or is this a typo in the NCRS TIM & JG from 1999 that should have read (ie. 0,1,or2) ?

Question #2: Chrome Hood and Rear Deck Vent Grilles in 1973 ?

Pg. 11 of the NPI-1-73, when giving General Information about the Corvette for 1973 in refering to the Grilles onthe hood and rear deck says: "Chrome is added to grilles on the hood and air outlets on the rear deck." My old NCRS TIM & JG (1999) refers on pg. 42 ref. to the hood grille says ".....vent grille which is also body color". In addition pg. 49 ref. rear deck vent grilles says "The vent grilles behind the rear window are body color." Does anyone know if any were produced with Chrome as listed in the NPI-1-73? Were any produced by GM but not installed on cars? or Does anyone know why this was changed to body color?

Again - probably stupid questions that have long since been asked and answered years ago, but nonetheless they are both curiosities to me because from what I read in the NPI-1-73 my car - equiped with a 454 M21 2.20 and a 3.55:1 rear end - should have the best option available to a 454 power wise and I just wanted to know the correct answer when people ask, and I just happen to like when a car has the Chrome vents on it.

Thanks, Jim

[Joe L.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

Maybe a stupid set of Questions, but here it goes - and let me know if this has been covered in the past and I will try to find it.

I recently picked up a manual called "New Product Information" - "Chevrolet 1973" (NPI-1-73), I'm sure I am not the first to ever see it. "This booklet highlights the 1973 product features that differ from the previous model year." It goes on to say...."All information, illustrations, and specifications in this booklet are based on the latest data available at the time of publication approval." By the NPI-1-73 am I to assume this was an early 1973 publication?


Question #1: M22 in 1973 ?

Pg. 116 of the NPI-1-73, lists available Manual Transmissions and only shows three options: 1. M20 3.11/2.54, 2. M20 2.52, and 3. M21 2.20. There is no M22 listed as base or as an option in 1973 for any vehicles. Now I have seen people online suggesting they have a 1973 Corvette with an M22 "Rock Crusher", Am I correct in assuming they are either wrong, mis-informed, or that they have a non original transmission? The NCRS TIM & JG that I have, dated (1999), on pg. 22 refers to an M22, Am I correct that this was included to insure no confusion regarding the aluminum case only or is it because there are cars with documented M22's in them from 1973? Also the next portion of the NCRS TIM & JG (1999) suggests that the second digit from the left in the Muncie 4-speed identifier should be (0,1, or 2). Does this mean that there should not be a "3" for 1973 or is this a typo in the NCRS TIM & JG from 1999 that should have read (ie. 0,1,or2) ?

Question #2: Chrome Hood and Rear Deck Vent Grilles in 1973 ?

Pg. 11 of the NPI-1-73, when giving General Information about the Corvette for 1973 in refering to the Grilles onthe hood and rear deck says: "Chrome is added to grilles on the hood and air outlets on the rear deck." My old NCRS TIM & JG (1999) refers on pg. 42 ref. to the hood grille says ".....vent grille which is also body color". In addition pg. 49 ref. rear deck vent grilles says "The vent grilles behind the rear window are body color." Does anyone know if any were produced with Chrome as listed in the NPI-1-73? Were any produced by GM but not installed on cars? or Does anyone know why this was changed to body color?

Again - probably stupid questions that have long since been asked and answered years ago, but nonetheless they are both curiosities to me because from what I read in the NPI-1-73 my car - equiped with a 454 M21 2.20 and a 3.55:1 rear end - should have the best option available to a 454 power wise and I just wanted to know the correct answer when people ask, and I just happen to like when a car has the Chrome vents on it.

Thanks, Jim

Jim------


As far as I know, NO 1973 Corvettes were originally built with M-22 transmission. So, if someone has such a car now, it was converted. That's easy enough to do.

As far as I know, NO 1973 Corvettes were originally built with chrome-finished rear deck grilles. All were body color. Chrome grilles were a once-popular customizing trick, though. Some folks might have got the idea cars were built that way. That's an incorrect idea.

[Michael W.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

Joe is correct on both points- No M22 or chrome grills in '73. As to whether an M20 or M21 is 'best' depends on the intended purpose of the car. I'll take the M20 any day.

[James B.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

Yes Joe, I agree to both your answers any thoughts though on why GM would say Chrome vents in the NPI-1-73, my guess, and this is purely irresponsible speculation ...since both my Father and my wifes father worked at GM during that time - mine in Research and Development, and me knowing how he would come home with stories of what they had been doing there, my guess would be... there are some GM Chrome Vent Grilles that were produced and likely put on some early cars and then removed? Lets see it would not be unlikely if at some point a youong kid was with his dad at the tech center and maybe saw some chrome grilles on a silver vette sportin a Swash Plate engine with oiling problems......... oops more irresponsible memories, I mean speculation. Hmmm.........

[James B.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

I disagree Michael, the M21 with 3.55 covers the rear of my car in a huge cluod of smoke and little bits of rubber!!!!!!!!!!! or dirt and rocks

[Michael W.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

I disagree Michael, the M21 with 3.55 covers the rear of my car in a huge cluod of smoke and little bits of rubber!!!!!!!!!!! or dirt and rocks

You'd do an even better job with an M20 then.

[James B.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

Now you know my math skills

[Michael F.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

You'd do an even better job with an M20 then.

Hard to beat that 2.54 first gear.

[Norris W.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

The confusion may come from the fact that the '73 transmissions had a BIG output shaft like the turbo 400 and M22 and also a lower drain plug previously not on M20/M21. I'm not sure exactly what year the changes took, place, but both of these characteristics seperated the M22 from the M20/M21 previously, however sometime in early '70s the changes were made. I have an M20 or M21 that I bought that was from an early '70's Corvette that was represented as being an M22 because of these two characteristics, and not knowing any better at the time I bought it without removing the side cover to inspect the gears, based on the fact that I had driven the car and it shifted fine and didn't pop out of any gears on decel.

[James B.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

Well M20 - M21 either way I am sure they are both fun, just the M21 is the only one I have so there for the funest in my barn. Still back to the question about Muncie Transmissions. Why the reference to the M22 in the manual for 73, just seems to muddy things up, and why does it say (0,1 or 2) and not (ie. 0,1 or 2) when clearly we're talking about a 73, or could it - should it read (0, 1, 2, or3) meaning you could have a 1970, 1971, 1972 or 1973 Muncie in a 1973? Hmmmm...

[Joe L.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

The confusion may come from the fact that the '73 transmissions had a BIG output shaft like the turbo 400 and M22 and also a lower drain plug previously not on M20/M21. I'm not sure exactly what year the changes took, place, but both of these characteristics seperated the M22 from the M20/M21 previously, however sometime in early '70s the changes were made. I have an M20 or M21 that I bought that was from an early '70's Corvette that was represented as being an M22 because of these two characteristics, and not knowing any better at the time I bought it without removing the side cover to inspect the gears, based on the fact that I had driven the car and it shifted fine and didn't pop out of any gears on decel.

Norris------


The output shaft changed for the 1971 model year for ALL Muncie variants. Some 1970 M-22 Muncies may have used the large output shaft but I don't think any were installed in Corvettes (of course, only a handful of 1970 Corvettes were equipped with M-22). I think the large output 1970 M-22's were used in LS-6 Chevelles.

[Patrick B.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

Norris------


The output shaft changed for the 1971 model year for ALL Muncie variants. Some 1970 M-22 Muncies may have used the large output shaft but I don't think any were installed in Corvettes (of course, only a handful of 1970 Corvettes were equipped with M-22). I think the large output 1970 M-22's were used in LS-6 Chevelles.

Joe------
I have a large output M-22 with a 70 Chevelle VIN stamped on it which proves your thought about 70 LS-6 Chevelles.

[Norris W.]

Re: M-22 in "73" -? and Vent grilles Chrome in "73" -?

Some 1970 M-22 Muncies may have used the large output shaft but I don't think any were installed in Corvettes (of course, only a handful of 1970 Corvettes were equipped with M-22). I think the large output 1970 M-22's were used in LS-6 Chevelles.

Both my LS6 Chevelle and LS6 El Camino with their original drivetrains have M22's with big output shafts. My '70 LS5 Corvette has a small output shaft. The original owner ordered it with the intention of modifying it for road racing (even though he ordered factory air convertible) I always figured it meant the M22 wasn't available in the 70 Corvette even though it's shown on the lists, since it was L88 only in '69. My thinking was that it was probably another casualty of the lack of LS6 or LS7 options for '70. After all this, and given the owner's preference at the time it makes me want to re examine the transmission and see if it is actually a small output M22. I have the build sheet but it's not readable in that area.