Hello,
I do have a 1989 Cummins with 727 trans and need to have an OD Transmission.
I know there are some Diesel 518 out there but rare to get one.
I might get A-518 Gasser 46RH Transmission and was wondering if you can morph those two.
Using the front/main case from the 727 with the cummins bellhousing and the tail and all internals from the Gasser 518?
Obvioulsy would need a Diesel Converter due to the different splines and as well the governor from the Diesel.
An overdrive unit will not bolt on to a 727 case.
Diesel got either the early 727 or later the 47 or 48 RH/RE, never the 46.
Not true, the 91.5-93 auto, O/D is a non lockup 46RH derivitive. The 47RH didn't come out until 94. It was never installed in the 1st gen chassis, requires a different engine to trans adapter, starter, and relocation of the crossmember, cooler lines, shift linkage and frame clearancing for the starter to fit in the early chassis. You would also need to shorten the driveshaft as the engine to trans adapter is about 1.125" thicker for lockup converter clearance.
You may also need the crossmember from an O/D truck, I don't recall what the 89 crossmembers looked like but the mounts and the trans to mount plate is different for the O/D. You could source thie plate and maybe the crossmember from a gasser if the frame is the same height. The 94-95 V10 47RH case is the same but that is probably even harder to find but with the exception of the governor and the converter it would work.
The internals of the gasser transmissions and diesels/V10's are different and I doubt the gasser stuff would hold up behind a diesel. This would include the O/D units as well. There is a lot you can do but start with a diesel 91.5-95 or 94-95 V10 trans.
