Tell Toyota that you will gladly fix the truck but they will have to give it back to you for 3 weeks in order for you to return it to stock. :-laf You can take the truck to reputable shop and have the engine replaced, then you can sell the KORE suspension, the tires and wheels, and the gears and LSD unit that you had installed.
I am sure that there is some one on this site that will gladly buy and swap those parts from your old truck to theirs. When they get it back it will be the stock '06 that you originally purchased.
The way I see it, those parts did not influence their decision to trade with you so they should more than offset the cost of any repairs that they may need to make to THEIR '06 CTD. Besides, they will be selling points for that truck.

The way I see it, those parts did not influence their decision to trade with you so they should more than offset the cost of any repairs that they may need to make to THEIR '06 CTD. Besides, they will be selling points for that truck.