1970 LT-1 Rear End

[Stephen B.]

I was thinking of purchasting a CFA 3.70 gear ratio case. According to the Judging Manual, it's not a Heavy Duty rear end. I looked in the NCRS 1953 to 1972 Specifications Guide and saw that CFA was only for 454. I'm confused. Which rear end are correct for a 1970 LT-1? I thought LT-1's had the heavy duty rear end.

[Terry M.]

Re: 1970 LT-1 Rear End

The older Spec Guides, mistakenly, listed the HD differentials as w/454. The later (read current) versions corrected that. If memory serves my 1970 has CFA, but I don't have access to those numbers at the moment. I'll see who posts what during the day, and confirm the differential in my car from home tonight.

BTW: The fact that the TIM&JG does not list CFA as HD does NOT mean that it is not. It only means the authors chose not to step in that pile of do-do. Chevrolet listed some differential codes as HD in their documents. Some folks equated that listing as something akin to the parts book listing "w/HD." NOT true. For 1969 to 1972 all Corvettes with M40 got the so-called HD differentials, of course so did LT1 and all Mark IV equipped models.

[John H.]

Re: 1970 LT-1 Rear End

I looked in the NCRS 1953 to 1972 Specifications Guide and saw that CFA was only for 454. I'm confused.

You need the current (Fourth Edition, Spring 2004) edition of the Spec Guide.

[Kenneth B.]

Re: 1970 LT-1 Rear End

I was thinking of purchasting a CFA 3.70 gear ratio case. According to the Judging Manual, it's not a Heavy Duty rear end. I looked in the NCRS 1953 to 1972 Specifications Guide and saw that CFA was only for 454. I'm confused. Which rear end are correct for a 1970 LT-1? I thought LT-1's had the heavy duty rear end.

MY 70 LT-1 with 4:11 is CFB-2-10 SN 3893 19,000 mi. Same # is on the dealer shipper
KEN

[Terry M.]

Re: 1970 LT-1 Rear End

CFA is what mine is.

[Stephen B.]

Re: 1970 LT-1 Rear End

I appreciate everyone's input.