It entirely depends on the damage. If the crank has chewed up the block and the bearing cap where the thrust washers go, then you are screwed. If not, then it is a degree of what damage has been done. There may not be enough material left to hold the washers in place. Only one washwer may have fallen out. You just cannot tell without looking. At best, this is a temp fix, and it will give you enough time to do something about finding an engine.

One thing is for sure, you should not be driving it like this. The crank is probably rubbing on the block and releasing copious amounts of metal shavings into the engine.

Yes, you need the thrust bearing set. It is a two piece set consisting of two half moon shaped washers. It ain't going to be fun, nor easy to do this with the engine in the truck. It is possible, but it will just take some time and a lot of disassembly. You may even have to unbolt and slide the tranny back a bit to get the last two bolts that hold the pan on.

Good Luck,
Michael