I am looking into swapping out the transmission in my '88 F150 300 I-6. Currently it has the Mazda-built Manual 5 speed with Overdrive (M5OD) which is the single bellhousing / case design. I've read on this newsgroup that this transmission is expensive to repair / replace and good for about 150k miles.

When it comes time to replace (which is soon), I would like to swap it out for the M4OD, if possible. Has anyone attempted this? Will I need to replace the clutch or do any mods like shortening the drive shaft?

Any helpful hints is apprecciated.