My 1989 W350 has 275K miles and the 727 is still working fine but I want to try to get some better mileage especially when running empty. I'm getting 13 when pulling or hauling a heavy load, travel trailer or cab over camper and atv trailer. Can run 60 mph at 2100 rpm and more power now with the intercooler and tweaked up pump a bit.

I am wondering what later transmission with an OD could be installed and increase mileage especially when empty. I understand an A518 was the first autotransmission installed in 1st generation trucks. (Right side Diff).

Any suggestions regarding this or alternative OD transmission installs for my truck and also replacement torque converters.
Thanks, Brent

 

If I were going to go OD, I would go all the way and do a 94/95 47RH and get the lockup as well. Mine dropped far more RPM when the LU happened than when OD engaged.

It will be significantly more both to get the core trans and to build it right, but that is the best trans you can get without getting stupid.

Either will bolt right to your current 23 spline 205, though both will require modified driveshafts for length, not sure about crossmember relocation.

Oh yea, with the 47RH you will need a second gen block adapter and starter, your current flywheel will remain.

 

Thanks,
I may seek out a shop that can handle the swap. I've heard about a toggle switch to shift to OD.

 

That's one way, check out the PATC pressure switch control of both LU and OD..... Towards the bottom, you can probably source your own parts a bit cheaper, but it shows you how to do it.

Towards the bottom of the page.

http://www.transmissioncenter.net/dodge.htm

 

thanks

 

The lockup torque converter is the weak link with the 47RH. If you can't afford the price of a triple disc, go with the A518 and a low stall torque converter. That is what I'm running.

 

Patc's controller is a joke. Ended up sending it back and just doing switches.

Best thing to do is wire it for switches then drive around with a pressure gauge attached to the trans. Figure out what pressures that trans makes at what mph. Then get corresponding pressure switches.