So I'm in the process of purchasing a 2000 gmc 1500 4x4. I want to basically transplant the drive train into the j20. I have no Idea what I'm doing but I have experience with older gm engines. I assume it would be easier having a complete vehicle to swap from. So how hard will it be? What are things to look out for? Can I use the transfer case from the chevy? I assume I should use the gas pedal from the chevy. Any advice?
It's a really simple process, it is just tedious. Do not cut any wires off the gmc except at the firewall until you start the process of pulling the wires using LT1swap.com which has all the wiring harness stand alone charts.
DEPENDING ON YEAR OF J20: You can use the tcase from the chevy, it will be best if it is a manual shift. The tail housing on the transmissions are different if you use manual shift vs electric shift, so if you do switch to an electric shift or to a manual (I don't know what you have) make sure you get the tail housing.
Novak and Flop shop have bolt in motor mounts, all you need to do is drill two holes on the transmission crossmember. Placement will be determined by these mounts- so easy. An inline pump will work but will be nosier. I'd suggest in tank pump but its a lot more work.
LT1Swap will also turn your computer into a stand alone computer tune- use them, best 85 bucks you and spend.
You do not use the gas pedal until 2003 and newer.
There is a GM part number for the throttle cable to adapt it to the jeep pedal and to the throttle body of the LS engine. I don't have it though, maybe someone will pip up. If no one does, PM me and I'll search for it.
Aside from wiring, fuel lines and pump (need high pressure fuel lines), and as long as your j20 is from the 80's. Everything else will bolt up without headache. You'll use your factory gauge sensors using a NPT to MM adapter from JEgs, (amazon about 12 bucks) and a Dakota digital speedo adapter.