2006 Explorer 4.6 v8 has no power to tow up mountains?

I am betting you do NOT have the factory HD trailer tow option !

If you are concerned about damaging the engine/transmission install an auxiliary transmission cooler and a temperature gauge.

BillyW wrote:
My older (97) 4.6 definitely didn't have enough pluck to tow our 6000ish lb trailer through the mountains until I upgraded the rear end from 3.55 to 4.10.

A excellent solution !

OP probably only needs a 3.73 axle unless he is going to be pulling more loads than he said.