i have a 1964 ford f100 with three on the transmission but every time i put it in third gear it will either go in smoothly and pop out into nutral or it will grind in to third gear and still pop out. ive been trying to find what the problem is all over the internet but i cant find anything so if i cant find out why can i put a 4 or 5 speed in it it is a 292 V8.

 

Maybe a bad synchro but you'll have much better luck posting in the f100 section. Just a friendly reminder that's all.

EDIT: here's where you want to post. these guys will be helpful : https://www.ford-trucks.com/forums/forum40/

 

Welcome to FTE

I've moved your question down to the forum that creich68 mentioned.
Good luck with it.

 

I haven't had these issues in years. I used to see this type of thing all the time with my 64 Econoline. I have heard on the slicks that either bad bushings in the linkage, or rotting(collapsing) cab supports can cause all sorts of shifting issues.

On your want to put a 5 speed in HOME T The only issue I heard about the t-5 Mustang transmission is that the shift point is way back, and so you will have to build a creative shifter because it comes through the floor under the seat.

 

Popping out of 3rd gear:

The two 2nd/3rd syncronizer brass blocker rings are worn.