D100 Pickup question for you:

You really have to understand”intended use”. When yours was born it’s intended use was”truck”. Now years later you are changing its use without changing how it was built. The bodies have not got heavier but the frames/suspension/power train have changed quite a bit in fifty some odd years. Be realistic on how you want it to perform before you start throwing money at it. I have found that trucks are mainly modified and the best and most efficient way is to buy a rusty bodied late model and switch. But that is your decision to make