I sold ibm espp stock that i recieved in 1991 and 1992 but i don't have any info for grant and share exercise dates.

[DDollar · Accepted solution]

Given how long ago that was, the specific dates won't have any impact on the tax treatment of the sale.  You can estimate or use "Various".  You will need to know your cost basis and the discount amount you received in order to properly report the sale.