Love it Ryon, I think if you have enough time to get everything checked and repaired this thing will surprise people. The Extreme was awesome, you must have a really early one from ’97ish though to have a 40mm. I had a ’99 and it came with a 40mm rear axle. You can get castor pills for it back in the day, they weren’t very common though.
I have another Extreme right now, you can have the spindles and 40mm axle off it. I’m pretty sure the axle is not an OTK axle however so it might be more trouble than its worth.