I have a 1993 f150 with the 300 straight six. I recently began pulling some bigger things than I should be with it I have 3.55 gears and want to better be able to pull the close to 10000 pounds I could have on it now. It can do it now but it works hard. I'm thinking of going to 4.10s but can't decide if I should change the whole axle and if I do what sort of issues with the installation can I expect. I know the driveshaft flange but are the leaf springs wider?? Any input and ideas would be awesome. Oh I have a 5 speed in it and have put the over 8600gvw clutch in.

 

You really shouldn't be towing over 5000# with that truck!

Not only is the rear axle marginal, so is the transmission. That's a light duty Mazda transmission with a known weak input shaft.

 

It doesn't have the original transmission anymore and I am aware of the towing capacity which is why I'm toying with the idea of a bigger rear axle or just getting a bigger truck lol

 

What did you do - swap a ZF into it?

I'd get a bigger truck - at least a F-250.