First... check your idler pulley and measure the diameter then check your tension assembly to see if they spin freely. On my 1990 Chevy K2500 350 5.7 w/AC I wanted to replace the pulley on the automatic tension assembly... not the idler pulley on the left side under the alternator. Seems most sites use the words for both interchangeably but that doesn't mean you'll get the correct pulley. The Dorman site states this pulley has a diameter of 76mm (about 3") but Amazon shows it as 4.5" and not only is that incorrect that's about the size of the pulley on the tension assembly... which I thought I was buying. So, I'm partly to blame in the purchasing error because I didn't do enough research first but I did rely on the measurements. I have now purchased the automatic tension mechanism that was at fault and it came with a wheel. I should have pulled the belt first and then checked the tension assembly but that's what happens when you think you know it all. However, at about 11 bucks this is a pretty good price and... since I now have one... I'll replace the idler pulley and clean all the other pulleys while the belt is off. I also noticed that the bolt that holds the wheel on was worn and the wheel would wobble a bit, overheat the belt and cause it to start coming apart. I went through about 3 belts in the last 15 years and probably didn't drive more than 5,000 miles... I thought it was just the belt. This is a solid wheel and includes instructions... like stating you need to make sure the vehicle isn't running before you start replacement. It also includes the bushing but without a bolt you may have a problem like I did. Well worth 5-stars and I've been pretty happy with the Dorman products I have purchased. I think Rock Auto has a great site to determine what parts fit and the Dorman site is also very good... I'll check a little better next time before I assume anything. I have noticed that many listings here and on that big auction site will use words to describe something like this item that aren't always applicable... like "Idler Tension Pulley"... and that is partly what led me to purchase the wrong item... and the fact that both parts look pretty much the same.In my application... as someone else mentioned... I had to use the old spacer/bushings and O-ring because the bushing that comes with this isn't correct... though that may not be the case in all applications.