Busted the collar on the column where the shifter inserts into the column? You might be able to find a replacement at a junkyard, but it won't be easy to come by. 3 on the tree is quite rare nowadays. What part of the 3 on the tree do you not understand? It's really quite simple when you break it down.
So far as a 4 speed goes, the only 4 speed conversion that I know of that is common is swapping to a np435 4 speed. This has the shifter bolted directly to the top of the trans IIRC, and will bolt right into your truck. You may need to snag a different driveline, along with cutting/welding a hole in the floorboard for the shifter to come through. You will find those lurking under the 3/4 ton and up trucks. Not to mention some buses etc.
The column shifted trannies work just fine, but you have a 1/2 ton pickup, so it will be fine so long as you don't try to pull a house behind it... or maybe it will...
My own personal preference is the 3 speed, just because I like the way that it works... plus people give you wierd looks as you are driving down the road in "Park" lol.
I would shoot for getting the current setup fixed if possible, and if not, then an np435 is what I recommend for a swap, since parts are easier to find. Good luck!
~THOR~