71 4.11 rear end

[Jeff M.]

Looking to replace my 3.70 rear end with a complete new 4.11 pig. any problem using one out of a c2?? Did they change the u joint sizes is all i would be worried about I believe.

[Joe L.]

Re: 71 4.11 rear end

jeff------

The pinion flange used for all 1971 Corvettes is different than the flange used for any 63-67 Corvette. The flanges are completely interchangeable, though, so they can be switched. The rest of the units are, basically, the same and completely interchangeable as a unit. It's best to stay away from 63-64 units, though. They use a different pinion flange which, although the u-joints are the same, have a different spline count and you cannot install a 71+ pinion flange on these units. They also use a different bolting arrangement for the forward mount, although you can still use them for later models by using the 63-64 bolt configuration.

There is also the stub axle difference between all big block and C3 some small blocks versus the most small blocks. However, this can easily be converted one way or the other at the time the unit is installed.

[Jeff M.]

Re: 71 4.11 rear end

Joe, thanks for the info. I was planning on purchasing a complete housing with u joint flange and ready to go with the exception of adding my new big block 71 axle stubs. Will this 67 unit bolt right in otherwise?

[Joe L.]

Re: 71 4.11 rear end

jeff-----

Yes, the 67 unit will bolt right in. However, just to be sure you understand, you'll have to change the pinion flange. The 67 pinion flange will not work with the 71 driveshaft (unless you use a conversion u-joint).

[Jeff M.]

Re: 71 4.11 rear end

what year rear will use the same pinion flange?? What is the correct part number?? how hard is it to find the correct flange

[Joe L.]

Re: 71 4.11 rear end

jeff-----

1) All 68-70 with THM and all 71-79 use the same pinion flange;

2) Part number is GM #3879208;

3) GM #3879208 is discontinued, so you can't get it from GM. There are a lot of these "around", though; it was not a Corvette-only piece. It was used on many 67-72 passenger cars with 1330 series u-joint. It MAY be available in the aftermarket, too.