timing belt replacement interval for 88 Stanza Wagon?

Hey all,

Bought my Stanza wagon three years ago with 138,000 miles on it. Now it's got 173,000 and I'm finally thinking about changing the timing belt because I'm moving to Alaska and have to sell it (don't ask why it's taken me this long to think about the timing belt...).
The last guy's maintanence records show that he had the belt changed at 90,000 miles. My Haynes manual doesn't specify a replacement interval for the CA20 belt. So, the question: I'm betting that I was supposed to change the belt 20,000 miles ago, but I'm hoping that it's somehow got a 90,000mi belt life. I don't feel good selling the car if it's about to die, but don't really want to do that work to sell it - it seems like a bear of a job on this car.

thanks for any info or thoughts.
Alex