i have a 97 k3500 and every time i put a new belt on it streches to the point were the tensioner bottoms out. new tensioner and gates belt and the vacuum pump it bypassed and the alt and compressor move freely when belt is off. the power steering pump feels ok. please help any suggestions greatly appreciated.

i dont know what your routing looks like but i assume you got a belt that is sized for your truck but with no vacuum pump? how much did the belt compress the tensioner, you might have to find a shorter belt to begin with. napa is pretty good about "needing belt like this but smaller" they have listings like that.

i got the belt from heath diesel and seemed to be the right size its just as the truck runs the tensioner keeps moving to bottom position not sure if i should go shorter on the belt

all belts stretch, usually they stretch an initial amount then level off. if you dont have any more adjustment you may have problems in the future with the water pump not turning and over heating your engine. if thats the case you are going to need a shorter belt

I'd just get a belt 10mm longer or so, large number on the belt indicates length in millimeters, the parts guys should know what you're talking about.