Transmission for Cummins 5.9 vs 6.7
Hi all -
I'm in heavy research mode as I'm looking to swap my 545 trans. I have a '99 24-valve Cummins 5.9 in a 30' Blue Bird. I want to get a more stout trans with lockup converter as a minimum, and would LOVE to get the RPMs under control with an OD option. I have a good lead on an MT643, but that would also come with a lot of conversion parts due to change in bellhousing size (I have an SAE3, and the MT is 2) and no OD. But I have a parts list and can pull the trigger on that idea.
HOWEVER - I can only do this once...and I'm not even sure I can afford the ONCE! ha ha. So before I do anything, I want to exhaust my search. A long train has lead me to what I think are my best 2 last options: the aforementioned 643, or possibly an Allison 2500 PTS (as suggested by a helpful Skoolie.net friend!).
Here is the question: I have a lead on a 2500 from a 6.7 Cummins. It is my understanding that the 5.9 and 6.7 are VERY similar, especially "externally." Is it a safe assumption that if a 2500 is coming from a 6.7, that it should bolt right up to a 5.9 (not just bell housing, but also flex plate, adapter, etc)? I'm under the assumption that when it comes to the TCM, I would have to buy that separately to match my application. I'm also assuming that a drive shaft shortening may also be on the table (also with the 643). But as far as the mechanics, should I assume they should match?
Thank you in advance for any clarifications on this!
Shane
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