I agree with Midnight Rebel, that is a lot of miles on a truck that is 10 years old.
When I was 19, I bought a '69 Bronco with 100+K miles on it. It was smoking pretty bad and I figured it needed valve guide seals ( those of us old enough to remember the 260/289/302/351W engines know that these engines were terrible for sealing the top of the engine) I figured as long as I had the valve covers off, I might as well pull the heads off, replace the valves, shave the heads a few thousands and replace any suspect valve springs and rocker arms. It ran like a bearcat after I put it back together for about 10 miles UNTILL the added pressure of the new top end blew past the rings on the bottom end and it smoked worse than ever!. Lesson learned? Parts wear out together, so any upgrade on one side puts added pressure on another side, whether that be the engine, transmission or rear end. No charge for the advice!