Here's what I have, 78 F150 short bed stepside 4x4. It was a 300 I6 manual trans NP205. I am going to convert it to a 460 C6. What I need to know is the proper length of the output shaft of the trans and adapter for this truck. Is it true there are only 2 sizes for my combo? What are they exactly? I currently have a C6 laying around with a 10.5" shaft. I was told it's a 4x4 trans but have yet to find out for sure.