Nice Cars!

I love the King Cab and i still race mine, very good truck.
If you still have the original transmission stay away from hi power brushless systems, stay in the 17.5 to 13.5 turns area, if brushed you can go safely down to 19T. Anything more strong will put the weak original ball diff in trouble and it will slip....
If you want to use hi power motors you have to look for a TTC transmission (the Super Astute one) or for a belt one (Lethal Weapon) but you enter in an "expansive field"....
About the body if you want a good one you can stay away from the original one and but a very good repro from teambluegoove (on the Bay), thay are cheap and very well done.
Hope this help.
Bye.
WWD