Can any one tell me what this housing was out of originally? The #'s on the bottom are: AVW 179 E1. I was told '74 BB/3.08. Thanks.
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Re: C2/C3 Pumpkin
Frank, I am looking in Alan Colvin's Corvette by the numbers book, and the format you show was used from 1971 - 1974. However, I am having trouble decoding your number if it is indeed correct. The first two digits, AV, should correlate to the original axle ratio. I found the AV code for 1969, and it was 3.08 posi, but they did not use julian dating for assembly until 1971. The 3rd digit, W, means the unit was assembled in Warren MI. The 179 is the Julian date for the year, self explanitory. The E stands for Eaton positraction. I don't see the 1 suffix after the E in the books, maybe it is a shift code. There was no 3.08 axle ratio for 1974, but there was for 1973, and it was AW. So, if you look carefully, and it is really AWW not AVW, then your unit is a 1973 3.08 positraction unit....Craig -
Re: C2/C3 Pumpkin - correction
My mistake on the shift code, BUT it should preceed the E for Eaton. In other words, it should be 1 E not E 1 as you state for the last two digits, and it is indeed the shift of mfg. I really suspect you have a 73 unit, and it should read AW W 179 1 E .....CraigComment
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Re: C2/C3 Pumpkin - correction
Thanks Craig; Before I cleaned the grease and chisled the paint off of it, it looked like "AWW" but after it was cleaned it looks like "AVW" and the end is E1 for sure. Any way to tell what engine? I does have the BB yokes.Comment
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Re: C2/C3 Pumpkin - correction
Frank-----
From about 1971 on, the cap-type yokes were used on some small blocks as well as all big blocks. For example, my brother was the original owner of a 1973 base engine small block and his car had the cap-type yokes. Consequently, there's no way to tell what engine that belonged to the car that this differential unit was originally installed in. However, it's really a moot point. The unit would be exactly the same regardless of which engine it was originally behind.In Appreciation of John HinckleyComment
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Re: C2/C3 Pumpkin - correction
Joe - my 74 L82 also has the cap yokes, not sure if the L82 vs L48 matters, but it is a 3.55 posi. I have owned it since 1977 and was the 3rd owner, and I know the car is original as I traced the lineage...CraigComment
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Re: C2/C3 Pumpkin - correction
Joe cap type yokes were also used on 1970 Corvettes. My origial owner 1970 350/300 has them, always has.Comment
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Re: C2/C3 Pumpkin - correction
I believe the heavy-duty yokes were used on BB, LT-1, and SB/auto applications. My '71 automatic has them. Are the above three automatics?Comment
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Re: C2/C3 Pumpkin - correction
Charlie-----
I can't speak for the above three. However, my brother's 1973 L-48 was a 4 speed and, as I mentioned previously, his car was originally equipped with the cap-type yokes.In Appreciation of John HinckleyComment
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Re: C2/C3 Pumpkin - correction
I have seen a number of SB M40 C3s with the caps, and I suspect that is the norm for SB M40 in 1968-1972 and maybe beyond. Not all LT1s got the caps. I am dismayed that mine did not. I suspect, but don't have the data to prove, that LT1s with the performance ratio option got them, but standard LT1 differential got the U-bolts.TerryComment
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Re: C2/C3 Pumpkin - correction
Mine is an M21 CR Muncie.......not auto..CraigComment
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