1965 L75: 3.55 rear end option or not?

[Roger P.]

Hi Guys,
My '65, L75 convertible has a 3.55 rear end which I believe is original to the car. However, someone told me that the 3.55 rear was not an option with a 300 HP engine. Is that correct? I find data that tells me that a 3.55 rear was an option from the base 3.36, but I can't find anything that says it wasn't available with a 300 HP engine. Can someone please help me with the facts?

Thank you,
Roger (50141)

[Duke W.]

Re: 1965 L75: 3.55 rear end option or not?

One good reference is the NCRS Spec Guide. Everyone should have one.

No, there was no 3.55 axle option with the 250 or 300 HP engines regardless of installed transmission.

I was an option with all other '65 engines.

Duke

[Roger P.]

Re: 1965 L75: 3.55 rear end option or not?

One good reference is the NCRS Spec Guide. Everyone should have one.

No, there was no 3.55 axle option with the 250 or 300 HP engines regardless of installed transmission.

I was an option with all other '65 engines.

Duke

Duke,
Thank you! As always, you are quick on the trigger with answers to my questions. So much for my original 3.55 axle . Was there any other posi rear end option in 1965 for an L75, or was the 3.36 the only posi available?

Roger (50141)

[Rob M.]

Re: 1965 L75: 3.55 rear end option or not?

Roger,

I believe 3:08 was an option with 300 horse cars as well as the 3:36. My '66 300 horse car has the 3:08 which I believe original. Not too quick off the line, but great on the road.

All the best

[Roger P.]

Re: 1965 L75: 3.55 rear end option or not?

Roger,

I believe 3:08 was an option with 300 horse cars as well as the 3:36. My '66 300 horse car has the 3:08 which I believe original. Not too quick off the line, but great on the road.

All the best

Rob,
Thank you for your reply. Yes, you are correct as I now remember seeing the 3.08 as a listed option. I guess somewhere along the line of 45 years, my original 3.36 rear end got replaced with a 3.55 axle. I would be very happy with a 3.08 or 3.36 to reduce the RPM's on the highway and increase the MPG's at the pump!

Roger (50141)

[Bill I.]

Re: 1965 L75: 3.55 rear end option or not?

My, how times have changed. In those days you wouldn't be caught dead with a 3.36 -3.08.
Everybody wanted 3.70 4.11's.
Guess we get older & smarter together. Bill

[Joe L.]

Re: 1965 L75: 3.55 rear end option or not?

Duke,
Thank you! As always, you are quick on the trigger with answers to my questions. So much for my original 3.55 axle . Was there any other posi rear end option in 1965 for an L75, or was the 3.36 the only posi available?

Roger (50141)

Roger------


Either the 3.36 or the 3.08 could be ordered with positraction for 1965.

The availability of only 3.36:1 and 3.08:1 with base engines (and L75 for 1963-1965) was not limited to 1965. The same rule applied for all 1962-74 base engines (and L-75). After 1974 there were a few excursions from the rule.

[Timothy B.]

Re: 1965 L75: 3.55 rear end option or not?

Roger,

If you ever decide to change the rear give consideration to the 3.36 ratio. The wide ratio transmission that's standard with L-75, and 3.36 is a nice combination for street driving.

The L-75 with the stock cam will pull nicely with this combo..

[Duke W.]

Re: 1965 L75: 3.55 rear end option or not?

With the 250/300 HP engines a 3.36 open diff was base for all transmissions, and it could be ordered with Positraction. 3.08 was optional with Powerglide and the four-speed, either open or Positraction.

With a 3.36 and WR four-speed the overall first gear is about the same as a CR and 3.70, so given the high low end torque of the 300 HP engine, this combination is pretty strong in normal driving.

The 3.08 is overall ten percent taller, and a nice highway gear turning about 3100 at 80 with 20 MPG fuel economy potential at legal freeway speeds.

Duke