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I have here a big block differential that is supposed to be a 3.08 from a 71 corvette and the numbers are H-25-0 which I guess to be Aug.25-1970 which would be right before the 1971 models and be destined to go in a 71 . The other set of numbers are AW W336 2 AW for 1971 is 3.08's but what is the W336 ? I haven't checked by turning the wheel and driveshaft to see if it is original . Been in storage and 27k. miles.
The W is for the Warren, MI plant that built it. 336 might be the 336th day of 1970 which would be Wednesday, Dec 2 or it might be that someone swapped out the 3:08s with 3:36s. You know the drill for the physical check so do that next (SAFELY).
AFAIK one that had a particular code stamped on the bottom flat surface of the housing next to where the cover bolts on. The guts are the same as small block destined differentials, the only physical difference being the side yokes. Bolt on caps to hold the stub axle U joints on BB units, and U bolts to hold em on the SB units.
I'll leave the set up details to you, as I won't have half your expertise in another 2 lifetimes.
I was told that it originally came out of a 71 big block 454 corvette and the numbers seem to verify that. I just want to make sure what I'm working with .. Not sure what the W336 2 means that is also stamped on the case.
There are variations among the years regarding the stampings. First pic is from a 65 unit I have that shows the date in a MM DD YY format (March 30, 1965). The second pic shows a 73 unit I picked up a few years ago. The AW is the ratio (3:08), the second W is for Warren (the plant that built it), the 184 is the Julian date (the 184th day of 1973 was July 3), the E is for Eaton (the posi carrier) and the 1 signifies it was built on the 1st shift. In this instance, the year needed to be derived from the housing cast date - D 4 3 - which is April 4, 1973.
There are variations among the years regarding the stampings. First pic is from a 65 unit I have that shows the date in a MM DD YY format (March 30, 1965). The second pic shows a 73 unit I picked up a few years ago. The AW is the ratio (3:08), the second W is for Warren (the plant that built it), the 184 is the Julian date (the 184th day of 1973 was July 3), the E is for Eaton (the posi carrier) and the 1 signifies it was built on the 1st shift. In this instance, the year needed to be derived from the housing cast date - D 4 3 - which is April 4, 1973.
OK so the 336 would be the day built in 1970 but where yours says E1 mine only has a 2 ?
AFAIK one that had a particular code stamped on the bottom flat surface of the housing next to where the cover bolts on. The guts are the same as small block destined differentials, the only physical difference being the side yokes. Bolt on caps to hold the stub axle U joints on BB units, and U bolts to hold em on the SB units.
I'll leave the set up details to you, as I won't have half your expertise in another 2 lifetimes.
Ah, very good grasshopper. I have seen many get taken by thinking a BB diff is somehow stronger, better, or worth more, it's not. I have seen plenty of BB posi cases cracked.
Anybody know what is a safe way to flush the unit before adding new gear oil and additive and is it ok to add more than one tube of posi additive when fully flushing the unit?
I was told that it originally came out of a 71 big block 454 corvette and the numbers seem to verify that. I just want to make sure what I'm working with .. Not sure what the W336 2 means that is also stamped on the case.
1971 differentials- what I would look at more than any number or stamping.
1- check the posi case
2- 10-18 spiders, not the best
3- check axle face dimension and hardness
4-Check ring gear bolt torque or replace with ARP
5-posi case is from the 68-71 run, ok it was better than the 63-68's but not as good as 72-79's.
6- check bearing cap fitment
7- check the LH side wall for gouging
I bought two tubes of posi additive since I totally drained the unit since it was out of the car . I turned it on the side so it drains completely. Then I read on the tube only one tube for 1-4 qts. Do not use more than recommended amount . Anybody use more and is it really needed ?
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71 Big Block Differential Ratio ID
