those numbers sound normal.... if you want to lower the temps you have 3 seperate ways of doing it... upgrade the stocker to the 6.0L or the V10 cooler, add a secondary cooler like the trucool one your talking about or get a secondary with a buit on fan like the one i run on my truck.... i never see over 150 during regular driving(fan not on) and over 180 towing(fan off) if i turn on the fan it will easily drop it down like 30degrees...
Stealth Automotive. Oil Coolers
let me know if you have any questions
-Raul