NEED NEW ENGINE

[JimT]

so probably gonna need more information about your truck to determine the correct engine replacement. make, model, YEAR, transmission (manual or auto?). Engine model years needs to match up with truck manufacture years to be in compliance with EPA regs. Basically you can't put an older model engine in a newer model truck. Gliders were getting around this by using older engines AND chassis and basically putting newer cabs on top.

I'm no expert on engine swaps, but going from one brand to another will require more parts and labor as piping and hoses and some wiring harnesses need to be changed to connect in different places. Other accessories, like a turbo, might not come with the engine and will also need to be replaced to match. And then there's probably going to be programming, both for the ECU and the truck, to match things up. If it's an autoshift transmission then there will probably be additional programming needed for that as well. And of course there's all the aftertreament components which are usually designed to function with specific engines, so there could be some changes needed there as well.

On the other hand, staying with the same engine would basically be a drop in replacement and would be cheaper and faster. If you want to switch engines manufacturers then the simpler and faster solution (though with current prices it might not be cheaper) might be to find a different truck with the engine and specs that you want. On the flip side, any used truck you buy will come with it's own set up unknowns, so there's no single best option.