I am swappin a 350 into a 66 c-10 that had a straight 6. I have the whole engine harness all the way to the computer inside the car. I can get more off of the car if needed. The car is a 1992 Buick Roadmaster if that helps. But my question is do I need to take the whole wiring harness including the fuse box. I have heard that I have all I need but Ive also heard I need the fusebox. I dont see why I would need the fusebox.

You cab do it either way but the easiest is to use the entire harness, fuse block and everthing. I did a direct swap from a 89 Suburban to a 72 Suburban and it worked great. Have fun hooking up your dash!!! That was the only tough part.