Damn, sorry to hear that man. Been in a similar place with a so called "factory remanufactured" transmission and "new in the box" clutch install which turned out to be an old transmission cleaned with acid and a used clutch plate with little life left in it. Judge found in my favor,$5 under WA small claims maximum allowable amount.

If you've asked him to replace the driveshaft and fix any damage it caused and he agrees great.
If not, photograph and document everything, if you have a witness have them sign a statement.
Have lawyer(paralegal,intern or secretay will actually do it) send him a quote for the damage on thier firms letterhead,
(this will cost you $50) and see what happens.
If he's smart he'll pay the damage to have someone else fix it and move on with his miserable life. Obviously you don't want him to touch your truck at this point.

I've been down this road with shady mechanics, don't go off half cocked and threaten him or do something stupid. If the judge in small claims court thinks your a hot head he or she dismiss the case and your on your own. Play by the rules and you'll get it fixed.
Go down to his shop with a loaded .44 and you'll end up in jail with a broken truck and seriously pissed off wife or worse.
I'd say at the very least he owe's you all your money back and a gas tank in at least the condition yours was in before the axle grenaded.