I'm having a real problem finding out what gears my rear end has. All I have are the casting numbers-NF 3896838. I found that is from a 1971 C10. Here is my confusion. I jacked it up and marked the drive shaft then turned the wheel and it went 2-1/4 turns for 1 shaft turn. That don't make sense! It has a 250 L6 and a SM465 4 speed (not orginal). There is no other ID on it.
Thanks from a new guy.
Jim
