It's easier to replace the drive axle assembly. Inspect the CV (rubber) boots on the other one. If they're ok and the axle isn't damaged or anything you can just leave it alone. The outer axle boots are prone to failure more so than the inners. HTH. -Jim
I would replace the axles on both sides at the same time if I had the budget.
But to answer your question, you can replace just just one.
Looking for a Used Grand Prix in your area?
CarGurus has 2,709 nationwide Grand Prix listings starting at $1,500.
Search Pontiac Grand Prix Questions
Pontiac Grand Prix Experts