[Antny]

Ok so I been having my lowering kit on since 06' and have a slight vibration at 50mph for as long as I can remember. I've been reading through the form and thinking it could be a piñon angle issue. I have 0 degree piñon angle and reading it should be -2 degrees pointing slightly down. I have no idea what size shim is in there but it is 15mm thick. Any ideas what size it could be?

 

[Throttle Jockey]

If you have a 0 degree angle and desire a -2 degree angle then you need 2 degree shims. When you install them make sure the thick part of the wedge is at the front so the snout of the differential points downwards to achieve the negative angle. If you install them backwards you will have a +2 degree angle.

Edit - Sorry, I see now that you're trying to get shims to replace existing shims. Most likely you have the factory shims in place now. IIRC factory shims are 2 degree so you may need 4 degree shims as replacements.

 

[Antny]

If you have a 0 degree angle and desire a -2 degree angle then you need 2 degree shims. When you install them make sure the thick part of the wedge is at the front so the snout of the differential points downwards to achieve the negative angle. If you install them backwards you will have a +2 degree angle.

Edit - Sorry, I see now that you're trying to get shims to replace existing shims. Most likely you have the factory shims in place now. IIRC factory shims are 2 degree so you may need 4 degree shims as replacements.

No there not factory shims I got them with the lowering kit back in the day.
I just need 2 degrees but don't want to stack on top each other I'm not sure if that would work. Trying to avoid removing to remeasure

 

[Throttle Jockey]

Contact the maker of the kit you used to lower the truck and ask them what degree shims they included with the kit.

Or remove the shims entirely and measure the pinion angle. This is the definitive way to answer your question and will only take about 30 minutes.