Transmission woes

[Bumpydog]

Hi all, looking for some advice. My 2004 Ram 1500 4x4 has been in the workshop now for several months with transmission issues. I paid about $3,500 to have the transmission overhauled as I was getting P0700 and codes for gears 3/4. All clutches/solenoids/sensors etc were replaced. After a week or so, the transmission wouldn't kick down and the tow/haul button did nothing. Disconnecting the battery temporarily solved the issue. Key to this, I guess, is the the speedo would sometimes stick around 45mph regardless of speed. Since that time, the rear diff speed and both front wheel speed sensors have been replaced. Live data is still showing a speed of 34mph, again, regardless of speed. The transmission has been removed again and a clutch pack changed. During all this, I had the ECU replaced (as the workshop said it appeared to have water damage). Now they are saying that the ABS module has water damage. (also, my power steering is not working at low revs, despite it being rebuilt twice in past few months)! Short of setting fire to the truck, does anyone have any other ideas (other than simply change the ABS module)? Now getting sick of this!

The part number on my unit is P55366040AC and my VIN is 1D7HU18D44J217240. Looking up that part number, it seems that the item is pretty scarce. Is there a compatible part number?

Lastly, the wiring diagrams show a Powertrain Control Module. Other articles refer to a Transmission Control Module. Same thing?

Also, I assume that the ECU (with 4 plugs/sockets on the side) is yet another module?

Assuming the TCM/PCM is a separate device, does this need programming if I get a used item from another vehicle?

Thanks, Malcolm
Co. Meath, Ireland