The transmission in my truck is a mystery. It's another chapter in a collaboration to make 1 good truck out of 3 or 4 bad ones :-)
I was told when I bought the truck it was the original transmission with the frame. The previous owners had already put an 86 cab on a 90 frame. It did have a 90 cummins motor in it, but I swapped it for a 94. Only reason being is that I drove the truck while Iwas rebuilding the other motor. Anyways, getting sidetracked. The transmission I assumed is a 518. They had told me they disabled the overdrive, for whatever reason. A friend took a look at it, and decided his best guess was that they had fibbed and its a 727. Recently, I looked at it closer, tried to get some numbers off the case to identify it for sure. In the process, I noticed a second plugin other than the NSS, located on the driverside of the case about where the pan ends in the back. It's above the pan. There's nothing hooked up to it, and I as far as I can tell there's no plugs to fit it that aren't plugged in.
Could this be the plug for the Overdrive switch? If it is, I know the overdrive switch works by grounding out the solenoid, but does anyone know which contact needs power and which is the ground? And would this have a lockup converter? I probably should've verified all this, but this spring I should be getting my 6spd, so I wasn't too concerned, but overdrive would be nice with diesel at 2.30 a gallon!

thanks.
Ian

 

As i understand it the dodge overdrive trans is "basicaly" a 727 with the overdrive in the tail .