Was decoding the numbers on my rear. Something does not work right here.

Date code on the carrier housing is -> K191 <- which tells me November 19, 1971.

Axle code is -> CM G335 2 E <- Which tells me a "3.42, Detroit Gear and Axle, Night Shift, Eaton Posi".

Problem is, the CM code does not show up until the 73 model year but the date code is late 71. Car is a 72 SS 350 4 speed which is normal to have the 3.42 posi.

Do I have a 73 rear or was there some "spillover" of the CM code in the 72 model year?

http://www.nastyz28.com/forum/gallery/data/500/date-code.JPG

http://www.nastyz28.com/forum/gallery/data/500/axle-code.JPG

Every book I have shows the CM didn't show up until 72, but we don't really know that the books are 100% correct. The best thing would be to try to get numbers from other 71 model cars built around the same time as yours and see if more show up.

That makes sense to me. For clarification, my car is a 72. Was just going by our host's site:

http://www.nastyz28.com/camaro/camaro72.php

Which doesn't show CM as being a valid code for 72.

Don't get me wrong, nastyz28 rocks! Learned a lot here. Just trying to figure it all out.....

Dates always trump codes. Your housing was cast in november 1971, so it's appropriate for a 1972 piece of equipment. Regardless of any codes stamped into it. Apparently "CM" didn't make it onto the official list of available axles, but in this case that's what it's representing.

Thanks all for the (as always) helpful feedback. Mike, that is my take as well. I think CM just did not make the list.