I have the drive train, computer & wiring from a 96 Dakota in my old Dodge truck.
The auto trans (which I assume is a 46RH?) has around 48,000 original miles on it now. It had 44,000 when installed into the truck, and I've driven the truck about 4,000 miles since. The transmission was working great, but the original aluminum & plastic radiator started leaking. I've installed a new cross flow aluminum radiator with the trans cooler in it. I believe everything was working well, but the weather turned colder shortly after the radiator install (low teens for high temps). The truck gets driven little during the winter, and I need to drive it across town (about 3 miles) before it starts warming up operating temp with the 195 stat (pretty normal around here), so the trans fluid probably barely reaches 160 degrees until I turn around and come home. Its all in town, so things like OD or torque converter lockup are pretty hard to notice.

About a month after the radiator install, I blew a trans cooler line off, but didn't know it until I was almost across town and the trans started slipping. I stopped driving (more accurately it stopped moving) about a block later where it was the only place I could get off the street. I reattached the cooler line, and put in 8 quarts of ATF4 from the Oreilles that was walking distance from where I stopped. It started up and drove it home, where I added another quart of ATF4 to bring it up to full. The transmission seems to still shift very smoothly, but leaving a stop it seems to slip (feels like letting a clutch out) until it starts rolling, but then feel fine, but I don't think the OD has been working since.

Now that the weather is warming up, I'm driving the truck a lot more. I'm pretty sure the OD does not work. Last weekend, the temps were in the mid 40s. I started the truck cold, and drove it about a mile on the highway, then stopped for about an hour, the drove it about a 1/2 mile (highway) and turned onto a bypass where I drove the truck about 10 miles at between 65 and 70 mph. The (factory) tack reads 3,000 rpm at 70 mph, 3:55 gears, motor at operating temp.

When I ran it out of fluid, did kill the OD, OD switches or the clutches in the trans? The fluid still looks good.
What do I need to check and fix? I have not yet dropped the trans pan, if I need a solenoid or something I'd rather order that and have it here before dropping the pan. Ideas?
Thanks
Gene