I have a stock (other than a K&N filter and smoke screw) '89 250 4X4 with a rebuilt 727. I would like an overdrive tranny as I do alot of freeway driving. I also tow a 10,000lb toy-hauler. What tranny would be a direct replacement and what is involved with making the O.D. work?
Also, I was wondering if I could swap that 727 behind my '71 440 big block...any ideas?
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the 4wd 727's in these trucks do have the real long extension housing on them, a 518 should be very close to the same length, as close as you will find anyways, the later transmissions are much shorter, you would also probably have to run the overdrive on a toggle switch

as for the 440, im fairly certain that the cummins bellhousing is different than the other 3 727 patters(slant 6-small block-big block) so the case wouldnt be any good to you for that, and the valving (shift points) are way off for a gas application, these things shift at 2500rpm or somewhere thereabouts under full load, and a non-smogger 440 is going to want to run up close to 6000 before the next gear