I have a 2010 4.0 XLT 4X4 about 95k miles. Ive been taking some road trips during the summer. I was driving in the heat of the Arizona summer day but the engine temp gauge didnt show the engine as hot. However about 3hrs into the drive i noticed i was smoking and sure enough i was leaking trans fluid. Took it to the dealer ship and the gaskets and seals wereblown in the transfer case. After that was fixed it happened again same conditions and was fixed under warranty. So is there any setups that are recommended for a external cooler for the trans?

 

An external trans cooler isn't going to do anything for the transfer case.

 

+1 ^^^

If its the transfer case then you need a rebuild
Transfer cases, like the transmissions and differentials, has a vent to allow fluid to heat up and expand, so pressure doesn't build up inside it that would blow out seals
On the first occurrence it could be from a blocked vent hose, but that would have been checked and cleaned, second occurrence would mean TOO MUCH heat is being generated inside transfer case, so rebuild time

Transfer case is a separate gear box, even though its connected/bolted to transmission there is no fluid exchange

A Manual transmission or transfer case should never need an external cooler even in Death Valley :)

Vent hoses should have a filter on the end so bugs don't get in and build nests blocking air flow in and out
Vent hose ends are also mounted up higher on 4x4s so water can't get in, usually underside of bed height