D'ya have the model numbers? If it's the one I think, it will take 95A, but you won't like the results. I ran 95 on a thinkpad 360cs (486/25 + 12M ram) and it ran well, but I spent a lot of time cleaning out all the unnecessary stuff and getting all the best drivers. It paced well with a default 95b install on a p100 + 16M ram.
As with all things, a little tuneup goes a long way.But a lot of times, if it came with 3.1, it's best to keep 3.1.