The 4 speed manual in my 6.9 f250 seems tired. Alot of slack in the gears, have to push the clutch all the way to the floor, after it gets hot when you stop and put it in first or reverse it makes a little been of a whining sound. At jiffy lube they refilled it with gear oil (80w90 i think) ?? Would a 5 or 6 speed directly bolt on the 6.9?

 

the ZF5 5spd is a very common swap, I believe you'll need a new bell housing, possibly new driveshaft, and a couple other things. I'd do a search on google and see what you can find

 

The ZF5 manual transmission will bolt right on to a 6.9 or 7.3 same bolt pattern. Now somethings to note about the ZF5 is the Duel Mass clutch is a piece of junk switch it out with the solid flywheel kit. Second is the transmission uses the ATF Mercon 3 not gear oil, next is to get the drive shaft that came with the ZF5 they used a shaft that has the U joint on it that is easy to slide in and out for repairs. Now last thing to do open the PTO doors and inspect the transmission in mine It was rolled and the magnet rolled up into the gears and shattered made it pop out of revers a lot. I Love the ZF5 I get great mileage out of it. I prefer it over any slip-o-matic any day.

 

wait the 4 speed is supposed to have mercon in it?

 

No The ZF5 five speed or to be owners manual Its a 4 speed with overdrive. The 4 speed previous to the ZF5 took gear oil.