1970 ZR1 LOOKING for rare part

[Gary B.]

Re: 1970 ZR1 LOOKING for rare part

Not the best picture, but this is the style I am use to seeing on them.
Gary B

[Ronald R.]

Re: 1970 ZR1 LOOKING for rare part

Is this a 69 or 70? thanks

[Kent S.]

Re: 1970 ZR1 LOOKING for rare part

Here's an ad for the guy I've used (not on Corvettes) but it works perfectly and he's a great guy to deal with.

[Ronald R.]

Re: 1970 ZR1 LOOKING for rare part

This is what I had on my L88, I think joe is right my speedometer was correct with no adapter until it broke!! thanks Ronnie

[Gary B.]

Re: 1970 ZR1 LOOKING for rare part

Picture is from a late 72. But the 70, 71 and 72's I have seen look like this.
Gary B

[Gary B.]

Re: 1970 ZR1 LOOKING for rare part

What the stamping on the adapter said.
Gary B

[Joe L.]

Re: 1970 ZR1 LOOKING for rare part

What the stamping on the adapter said.
Gary B

Gary------


The GM #6477965 speedometer adapter pictured was used for 1970 Corvettes with wide ratio M-20 4 speed and 3.55:1, 3.70:1, and 4.11:1 rear gear ratios. Of course, no 1970 ZR-1 was ever originally equipped with such a transmission.

The 6477965 was also used for 1971-72 Corvettes with 4.11:1 rear gear ratio.

Speedometer adapter GM #6477966 was used for 1970 Corvettes with close ratio M-21 4 speed and 3.08:1 and 3.36:1 rear gear ratio.

[Terry L.]

Re: 1970 ZR1 LOOKING for rare part

My 70 LT1 has a 4:11 with this adapter, I also think I have a M21. I

What the stamping on the adapter said.
Gary B

[Joe L.]

Re: 1970 ZR1 LOOKING for rare part

My 70 LT1 has a 4:11 with this adapter, I also think I have a M21. I

Terry------


I do not understand why you would have an adapter with a 1970 LT-1 unless it's actually a wide ratio with 3.36:1 or 3.55:1.

Do you have the actual rear end code, transmission code, adapter part number, and casting number of the transmission extension housing?

[Gary B.]

Re: 1970 ZR1 LOOKING for rare part

This is from a 72, Automatic with a 3:36 Differential.
Gary B

[Terry L.]

[Wayne M.]

Re: 1970 ZR1 LOOKING for rare part

Here's the chart from the 1970 P&A30B parts catalog (Corvette only). Also has chart for 1968 and 1969. Also two Stewart-Warner units. Sorry about the orientation of the chart -- the original is OK.

[Joe L.]

Re: 1970 ZR1 LOOKING for rare part

This is from a 72, Automatic with a 3:36 Differential.
Gary B

Gary------


The 1972 with THM-400 and 3.36:1 application did use a speedometer adapter and the part number should be GM #6477964 if it's original.

[Dick W.]

Re: 1970 ZR1 LOOKING for rare part

Gary------


The 1972 with THM-400 and 3.36:1 application did use a speedometer adapter and the part number should be GM #6477964 if it's original.

Joe, never seen one with a GM #. Always a Stewart Warner and the ratio as shown in another post in this thread. First # is the input and the second is the output. For instance the one shown had a 1 input and .834 output.

Stewart Warner does not manufacture these any more, S S White is the source.

[Joe L.]

Re: 1970 ZR1 LOOKING for rare part

Joe, never seen one with a GM #. Always a Stewart Warner and the ratio as shown in another post in this thread. First # is the input and the second is the output. For instance the one shown had a 1 input and .834 output.

Stewart Warner does not manufacture these any more, S S White is the source.

Dick------

The one shown above in Terry's #23 post has both the GM part number and ratio.

Both the AC Division of GM and Stewart-Warner manufactured these speedometer adapters. In fact, the one in Terry's post was manufactured by AC. I think (but I'm not sure) that units manufactured by AC had a seven digit part number beginning with "64" as this was a series of part numbers assigned to the AC Division. Many original speedometer adapters had Chevrolet part numbers (seven digit part numbers beginning with "38" or "39"). I suppose these may have been either of AC or Stewart-Warner manufacture. It could have been that units manufactured by AC had dual part numbers-----both AC Division and Chevrolet.