The 6.5L diesel utilizes a pulley diameter unique to the diesel from all the GM gasoline engine counterparts. The 6.5L diesel uses the alternator RPM for the tachometer. The problem comes in to play when you buy a new or reman alternator. The rebuilders almost exclusively use the gas alternator pulley which is readily available. The diesel pulley is no longer available.
When this gasoline version is used, the rpms on the dash are no longer correct. The 2nd, even larger issue, is the belt tensioner falls out of range and the belt is too long causing a squeaky belt and shorter belt life. Changing to this pulley fixes the dash rpms, brings the belt tensioner back to center and provides proper belt tension for maximum life.
6061 aluminum anodized for corrosion resistance.
How to tell if you have the wrong pulley on your vehicle? Measure the outside diameter of the pulley flange. You do not need to pull the belt off measuring this way. If your pulley is approximately 2.36" OD, you have the wrong one and need ours.
