I have a friend that has an original 53 f100 that he restored.Its an original flathead V8 with original 4 speed trans.The problem is he wants to drive the truck on a regular basis in the summertime but the rearend gearing is 3.91 : 1 and the RPMs are off the charts .He wants to install a 9" ford rear in it .Has anyone done this,and what gears did you use? What did you have to do for the driveshaft? The rear is a 1970 F100 so it should drop right in and use the original E-brake, from what I've read.
Any help he could get would be great.This is a great forum!

 

I'm just finishing the 9 inch swap from 70 1/2 ton into my 51 and your right it can be a simple drop in like you said. For gearing I using 3.50 gear set, as for the drive shaft. There are plenty of shop that specialize in drive shafts if you end up having to shorten one such as in my case. I've got a thread on here called Another piece of the puzzle, check it out.

 

Thanks for the question and response. I am in the process of doing this very thing. The 9" rear is almost in and the flathead will soon follow. I'll check out the links. Any others that you know of, please post and I'll check those out as well.