I have a 1999 GMC Yukon SLT with a 4 year old motor and stock transmission it in. When I crank it it has a grinding noise from the starter/back of the motor area. Just replaced the starter a month ago. Any ideas?

Hello, sounds like the starter motor you've installed is not working as it should. Alternatively, there could be missing or damaged teeth on the ring gear that the starter mates to on the back of the engine - also referred to as a flywheel. I'd remove the starter and slowly turn the engine manually to inspect the ring gear teeth -- if all intact, replace the starter motor and recheck operation. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops