The 545 is a good size for a pickup, but they just arent that strong. They can be made to handle it, but it gets spendy pretty quick. The converter not locking up is a big issue with a lot of swappers, as they create a lot of heat and excess rpm. I've seen the 6V53 on youtube, so it will fit. They're really heavy for the power they make. You could make more power with other diesels, but nothing sounds like a Detroit.