1970 LT1 protectoplate question

[Kenneth Champagne]

Was wondering if anyone could help me decode my protectoplate on my 70 corvette.....in the 2nd row where the rear axle code is usually imprinted it reads CFB before the build date. Can anyone help me? Thanks in advance!

[Terry M.]

Re: 1970 LT1 protectoplate question

CFB= 4:11 That is what was originally installed.

[Kenneth Champagne]

Re: 1970 LT1 protectoplate question

thank you Terry!

[Jim T.]

Re: 1970 LT1 protectoplate question

The 68-82 NCRS Specification Guide lists the CFB as 4.11 and also as Heavy Duty Positraction (454). Must be a story as to how it ended up in a LT-1.

[Terry M.]

Re: 1970 LT1 protectoplate question

The Chevrolet lists of the differential codes do not show those applications as 454 - they simply list them as HD. The latest Spec Guide (Spring 2004) corrects that for 1970+. It is still there for 1968-69.

[Jim T.]

Re: 1970 LT1 protectoplate question

Terry my 68-82 NCRS Specifications Guide is Volume Two-Second Edition-First Printing-Spring 1997. My early copy also lists the CAV 3.08:1 rear in my 70 as Standard (454). It is the heavy duty unit with the strap type retainers for the u-joints with a 350 Turbo 400. From what I understand any 70 differential that left the factory with stap type retainers is a heavy duty unit.