Trans swap question

[Dannomanno]

Hey guys I have an 85 f-350 dually with the 6.9 and c-6 3spd auto. I have a top speed of between 55-60mph at about 3000-3500. My question is, can I swap a newer trans from say a 7.3 into mine? I just need something that can get me up to highway speeds (70-75mph). I would like to keep the gearing the same, (4:10) I believe because I tow my 29ft fifth wheel and haul alot of heavy loads.

So bassicaly what trans models will "Bolt on" to my 6.9 IDI?



Thanks in advance.

[351fifty]

doesnt the 6.9 idi have the same bolt pattern for the 7.3 idi? if so you can use them all, zf5, i think a zf6 would even work, but the e40d from a powerstroke wont work, kause its run by the pcm, so 95+ no go on auto, good luck