If while towing you drop in and out of OD - turn it off.
If it doesn't drop out leave it on.
Simple.
This. Don't go through town or up hills with it on. Constant in and out of OD can weaken the clutches and that's the Achilles heel of the RFE.
Ok. Does pulling with it OFF make the transmission run cooler?
No, because you aren't in lockup, so in addition to the heat created from towing there will be more from slippage.
His truck is a 02. Suspect that is a 55RFE. Fully agree, always use tow mode OD off. Our 03 5.7 towed for years. Following the owners manual tow instructions, never had a problem. You DO NOT want to tow in OD.
45RFE on the 02 4.7 (unless the TCM mod has been performed)
When you press the button on the end of the gear ****,,,,on my 03. Press once reads OD Off. Press twice it reads tow.
Only when equipped with factory tow package
Hmmm, what's the difference in OD Off and Tow?? But when I push mine again it just turns the OD back on. Unless you have to push it twice real fast or something...
Don't have factory tow package
Is there a aftermarket Trans temp gauge I can install to physically monitor the temps or is there such a thing?
Lots of options here
Do you have a transmission cooler?
ALL 3rd gen Rams (with automatics) have external transmission coolers, they come in three different sizes, basically 1/2, 3/4 and 1 ton. Completely interchangeable. I switched to the 1 ton years ago.
there's usually a heat exchange in the radiator dedicated to the trans fluid. you can route the trans fluid to a cooler, and bypass the radiator altogether so it is only running through the cooler you install. you should be able to trace the hard lines and figure out the routing
3rd gen Rams do not have a trans cooler built in to the radiator. It's external in front of the rad along with the PS cooler.