1966 Rear End Identification

[Gerald C.]

The code on the rear end is FA 071265

If I look up this FA code in the NCRS Corvette Specifications Guide, this FA is shown as a 3:70 for a 427. Yet if I look the same code in Noland Adams Restoration Guide, it shows the code being related to a 3:70 for a 327.

Conflict of information??? Can someone help me distinguish between these two reliable sources of information?

Thanks,

Jerry

[Wayne L.]

Re: 1966 Rear End Identification

Alan Colvin's "Corvette by the numbers" shows 3.70:1 for a 427 engine. IIRC, codes starting with "F" were all for big blocks.

[Joe L.]

Re: 1966 Rear End Identification

The code on the rear end is FA 071265

If I look up this FA code in the NCRS Corvette Specifications Guide, this FA is shown as a 3:70 for a 427. Yet if I look the same code in Noland Adams Restoration Guide, it shows the code being related to a 3:70 for a 327.

Conflict of information??? Can someone help me distinguish between these two reliable sources of information?

Thanks,

Jerry

Jerry------

"FA" is the code for a 3.70:1 positraction axle ratio with 427 (all 427's were positraction). The code for 1966 327 with 3.70:1 positraction axle is "AO". The only difference between the 2 carrier assemblies is that the "FA" coded has cap type stub axles. The "AO" coded has u-bolt type stub axles.

[Wayne L.]

Re: 1966 Rear End Identification

And the NCRS 1966 TIM & JG, and the NCRS specifications guide both agree with Joe, etc.

[Gary R.]

Re: 1966 Rear End Identification

Jerry------

" The only difference between the 2 carrier assemblies is that the "FA" coded has cap type stub axles. The "AO" coded has u-bolt type stub axles.

Hi Jerry,
Joe brought up a very good point here, while not specific to your question it is relevant to guys looking to buy used differentials. Many times I have heard guys paying more then a used differential is worth only because it is a BB differential, as if that was somehow stronger then the SB diff's. This a myth, the only difference is the stamping and the axles. I have never seen an axle fail at the yoke, twisted splines and worn faces yes. The BB diff's have the same issues the SB ones do. Now the value to a car to have the correct date and stamping is another story.

[Gerald C.]

Re: 1966 Rear End Identification

Thanks everyone,

So I guess Nolan Adams Restoration guide is incorrect?

[Joe L.]

Re: 1966 Rear End Identification

Thanks everyone,

So I guess Nolan Adams Restoration guide is incorrect?

Gerald------


If he says that the "FA" code is for a 327, then he's incorrect.

By the way, GM also says that "FA" is the code for 1966-67 with positraction and 427.

[Wayne M.]

Re: 1966 Rear End Identification

Thanks everyone,

So I guess Nolan Adams Restoration guide is incorrect?

No, he's correct, as you are reading it from the list of ECL's (exception control letters) for the G81 (posi) option [page 342 for 1966 MY].

The window sticker posi code for this car would have read: 02G81FA.

[Gary R.]

Re: 1966 Rear End Identification

I checked one of my books for 1966, the BB cars were

AT= 308
AU = 336
AZ= 355
FA =370
FB =411
FC= 456