because my current unit is the factory, open rear that came with the 326. Given that the 326 has been replaced by a 455, it would be nice to make better use of the power
Understood. Depending upon the 455 you've built there are several ways to go. If you aren't talking hugely more than stock 455 and have something like a 3.08 already(Firebob's question), you may be able to just install an aftermarket posi unit. Obviously, swapping in a known rear end and making the necessary modifications to spring perches, driveshaft, u-joint, etc. is another viable direction. Lots of choices, that's why the questions.
1968 400 Coupe, verdoro green, black vinyl top 1968 400 Convertible, verdoro green, black top 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver)