As an FYI, I'm pretty sure the '73 Riv had 3.23 posi as an option, while the '71/'72 cars were available with 3.42. Either way, that a pretty good price for a full rear. There's been ring/pinion/carriers on this board for similar prices.
This rear would have two upper control arms. I believe your rear only has one? Now the "guts" might transfer over, but you'd do well to read the sticky at the top of the "boatload of fun" section on rears to confirm (bearing sizes might be different). Buick seemed to like to do a lot of "one year only" specials in the late 60's. ou:
I think I will just hold out untill I find the correct rear with the gears I want. Much easyr to swap out when needed.
