Hey, I have a pretty simple question.

I'm looking at buying a 96 850 glt wagon. The current owner bought it when it was a little over 100,000 miles, and was told the timing belt was changed at 90k. It is currently at 158k. The current owner says the timing belt needs to be replaced every 90,000 miles. The automechanic that works on my 240 says it needs to be changed every 60,000 miles. Finally, I was searching on google and found something that said every 70,000 miles. Does anybody happen to know which it should be? It is important to know before I buy the car, as I will want to negotiate it into the deal if I need to get a new timing belt right away.
thanks!