I have an 84 buick regal with a 350 chevy motor i want 2 put a posi on it 3.42 or 3.73, should i put a whole rear end on or change the differential, which is cheaper?
Also do know what rear ends match up? Please help!

If you must do this get a crossover for the entire differential from a salvage yard. I suggest don't touch it at all but do what you want. Speedo will be off and that will be an issue on it's own,

T
_________________________________________

Tom Greenleaf - MetroWest, Boston