You can try!! How much is still owed for the repo? Can you pay it off? Or make arrangements for her to pay it? And then send GW letters for removal!
Unfortunately creditors don't care what your divorce papers said if you are on the loan then you are equally responsible! I was in a similar situation recently, not a repo, but years worth of late payments almst repoed 3 times! Loan was finally paid in full and I begged the bank to remove the late payments because it was actually my wifes car in the separation, yet they never sent me notice of any lates or almost repos.. No dice, the Bank wouldn't do anything about it!
Since you were on the loan, the bank can still hold you accountable for the late payments and/or unpaid balance. I agree that your best shot is to try to send a GW letter to them explaining the situation, perhaps they will help you out.