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Diff and gearbox numbers

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GPJ80:
Hi there , trying to determine what diff and gearbox i have in my 1970 , The diff numbers are 1CA04 20 70 W and was wondering if anyone knows where the numbers can be found on the 4-speed gearbox , Its probally just the standard M21

jolinari:

--- Quote ---Originally posted by GPJ80
Hi there , trying to determine what diff and gearbox i have in my 1970 , The diff numbers are 1CA04 20 70 W and was wondering if anyone knows where the numbers can be found on the 4-speed gearbox , Its probally just the standard M21
--- End quote ---


Do u have  a letter missing after the CA? Can you comfirm the above numbers?

Have you got the protecto plate of the vehicle?

jolinari:

--- Quote ---Originally posted by GPJ80
Hi there , trying to determine what diff and gearbox i have in my 1970 , The diff numbers are 1CA04 20 70 W
--- End quote ---


 If the "0" is actually an "O" and not any other character, then what you have is a 3.70:1 positraction axle originally used with a 350 cid engine. That means the engine would have to be an L-46 or an LT-1


--- Quote ---Originally posted by GPJ80
if anyone knows where the numbers can be found on the 4-speed gearbox , Its probally just the standard M21
--- End quote ---



The transmission production code and VIN derivative will be found stamped vertically on the right side (passenger side) of the MAIN CASE just forward of where the extension housing/ rear bearing retainer plate attaches. The production code will begin with a "P" and will end with an "A", "B", or "C".

A= 2.56:1 wide ratio (M-20)
B= 2.20:1 close ratio (M-21)
C= 2.20:1 HD close ratio (M-22)



NCRS SOURCE

GPJ80:
Yeah not sure , the numbers on the diff are how i have seen them , Its hard to see whether or not its  a O or a 0 because all the O are the same size and shape , Whats the protecto plate , And the gearbox number i checked it , its POE04B . How can i find out what motor it came out with because i know now that the 350 that is in it is a CKW motor out of 72 model but has had LT1 Spec done to it

jolinari:

--- Quote ---Originally posted by GPJ80
 Whats the protecto plate?
--- End quote ---


The Protect-O-Plate was furnished with all chevrolet cars (65-72)and was a metal plate imprinted at the assembly plant. The plate contained information on various standard or optional equipment. You may determine from the imprinted information on the plate the type of engine, transmission, rear axle, exterior color, the month the vehicle was produced, and other basic vehicle information.
Note: This plate was included with the warranty book and was not attached to the car.

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