Hello Guys I have a 84 chevy scottsdale P/U 4x4 with a 350 Big block motor I plan to swap the motor out and insert a Duramax 6.5L Diesel with an Allison 1000 Transmission 6 speed Manule does anyone knows if I would have to change the rearend or install a computer chip. Any advise will be very greatfull or should I just keep it gasoline.
Depending on driving style that combo could eat your front and rear axles for lunch.
I'd recommend dana 60's front and rear.
You'll need the whole engine harness, engine, and transmission computers, fuel system (tank & pump), radiator, and the donor needs to be a 4x4 so you can get the transfer case also. Additionally you'll need to source the clutch pedal brackets and possibly fab some items to make the manual work.
This is a big project that could take months to work out. If your doing the job be prepared for lots of frustration and busted knuckles. If your paying to have it done it'll cost.
Is it viable ? Yes, but I wouldnt undertake it unless you have a lot of mechanical experience, whether your doing the work or farming it out.
With fuel prices like they are this swap makes sense but it'll take a long time to pay itself off.