good to hear you got it figured out. I changed out my thermostat a while back and the seal still felt alright. I had a little drop on the temp gauge after I had done the job. I read later that they say to replace the seal regardless. then I looked for the tool to press it in, and they want like $50 for it (not including the handle sold separately pff) . i'm gonna be doing some other work on the truck soon and I think i'm gonna drop the money for the tool and do the job as they say to. I thought about trying to make something like yall did but feel like its something I don't wanna mess with.......glad it worked for you

oh yeah, meant to also add, if you have to tear back into that thing for some reason, I've read to be careful tightening the bolts down a little at a time and keep them even as tightening. that housing can get fragile over time and are becoming impossible to find.