FWIW, a new shift knob isn't all that expensive. and installing it properly isn't very difficult. Believe it or not, they're still available at the dealer.
It's actually designed to be an interference fit. The replacement knob has a smooth inside surface, not splined like the lever is. You're supposed to heat up the knob (I put it in a pot of water and heated the water to boiling for a few minutes), then immediately slide the knob onto the shift lever. It's critical to get the knob in place while it's still as hot as possible. You may need to give the knob a few taps with a rubber mallet, but it should go all the way in. As the knob cools and the rubber contracts, it'll form-fit around the splines and hold itself in place.
I've done this three times now (got new knobs for my T-19 shifter and transfer case shifter shortly after I got the truck because the old ones kept slipping off, then another new knob when I put the ZF in), and I've never had a replacement knob come off. FWIW you shouldn't need to remove the knob again unless you're replacing the rubber shifter boot. If you need to remove the knob, the best thing to do is heat it up again and it should just slide off once it's hot. I don't know if it can be re-installed once it's been removed, but I would guess not.
Just my $.02...good luck!
