Sandbox

Ok so I talked to my local parts store and told them I had just bought an '88 toyota pickup that has obviously been poorly taken care of. One of the things they recommended was changing the transmission fluid and filter (auto transmission). The guy looked in the computer and asked if I had a 14 or 19 bolt transmission, after I went outside and counted them he came back with a filter kit containing a filter, thin gasket that fits the filter, and a thicker gasket that fits the pan.
So I got the truck up on jack stands, drained the oil, got all the bolts out, and couldn't get the pan off. Upon closer inspection it turns out someone used blue RTV instead of a gasket at some point. I tried to scrape it out with a razor blade, and tried to pry it off with everything I could find but it just won't budge. Eventually after about an hour of trying I decided to just put the bolts back in. I figured if it's got RTV on it someone must have replaced the filter at some point (best guess 100k?), and there is only 164k miles on the truck so it probably doesn't have to be changed anyway.
I filled it back up with transmission fluid and cleaned the outside of the pan with degreaser and towels. I'll let it sit overnight and see if it leaks.
Any suggestions? Based on what I've seen am I making a bad choice or does it sound reasonable?