Dude has legit reviews on Google. Seemed very knowledgeable, at least for two knuckleheads like us. Seems he does all types of rear ends so not worried if he doesn't know the GM years by heart. He said he's been doing it 12 years and sounds like a younger guy. We sprung a lot of info on him over the phone out of the blue so could always be a little miscommunication. I'm sure we'll get it sorted.If the rearend guy is telling you that you are ( right on the cusp from transition from 8.2" to 8.5" ) I would not use him, he doesn't know that the 8.5" came out in the 1971 Camaro, and in 1972 Novas, and other GM cars, it was GM's replacment for the 12 bolt, If it is the orginial rearend in his 1974 it will be an 8.5". I would go with the Eaton Posi. Look through this and you might be able to get the numbers off the axle tube and know what gears it came with, no guarantee that they haven't been changed though, also it shows you how to tell the difference between the 8.2" and 8.5"
Also why the Eaton Posi? Just wondering. He said if we have the 8.5" (I'm thinking we do but will verify with my uncle when he gets off work) then he could go Eaton, AAM, or Motive helical gears, if that's what we want. My Uncle just wants the one that is less maintenance that will get rid of the 1 wheel peel. Not that he is going to be doing much burnouts but nevertheless he wants it lol.