Are there any companies out there that offer custom fifth gearset? I'm currently running a .685 fifth in an F-series trans with a 4.062FD, and would like something quite a bit taller for the highway. A .600 fifth would be just about perfect.

 

Houseman might make one. Won't be cheap though.

 

So that's it, huh? Has anyone ever tried interchanging H/F and K series gears, or perhaps are the helical angles opposite because of the direction the two boxes spin?

 

I once spoke to M factory - they said if we could provide the quantity as in 10+ buyers they would make it.

Had spoken to them for some D series gears back in the day.

But sounds like a superb plan to have a taller 5th, should bump the top speed.

Regards

 

You can try other places but most shops with the capability to design and make gears won't do a one off gear.