1971 power teams

[Vincent F.]

My car has a 4sp M21 220.1 tranny,and a 3.70 rear.According to NCRS power teams guide this setup was only avail in LT1 cars,Is this true or not.The C3 NCRS judge Chuck Berge told me you could get any tranny with any rear set up you wanted.Whats up with this

[Chuck S.]

Re: 1971 power teams

According to the spec book it's slightly more complicated that you said. The LT1 would be the only SMALL BLOCK available with the M21, and (as you said) the only engine available with the M21 and 3.70 rear axle combination.

If you have the 68-82 NCRS Corvette Spec Guide, it's under 71 in Power Train Combinations. Basically, for an LT1, you could get either the M20 or the M21 with three possible axle ratios (Standard, Economy, Performance), but the three available axle ratios were different for the M20 (3.70, 3.55, 4.11) and the M21 (3.55, 3.36, 3.70).

Base engine was only available with the M20 and the M40 using 3.08 or 3.36 axle ratios. The LS5 could be had with the M20, M21, or M40, but not all axle ratios. The LS6 was available with M21, M22, or M40.

[Chuck S.]

More...

Chuck was probably referring to the possibility of a COPO order. In those days, there was some flexibility in ordering colors or power train combinations outside of those standard offerings by GM. If you happen to have a COPO car with a non-standard feature judged by NCRS, you have to have the COPO order documented, or any non-standard feature will see a deduct.

I'm told COPO orders are impossible today, however, I have heard of non-standard exterior/interior combinations on C6s that are not acknowledged by GM. Even in the old days, COPO probably wasn't being advertised by the dealers as something that could be done.

[Vincent F.]

Re: More...

Thanks Chuck,I am trying to authenticate my 71 LT1,unforturnatly I have no papers on this car,It does have the M21-370 rear with vin on trans