Timing Belt? Help!
 

Have a 2000 Chevy Suburban 1500 4wd with 155,000 miles. Getting sounds from engine as accelerate in lower gears. Sounds almost like belt squeek, but also has almost a low grinding or vibrating sound. Not sure if this is the beginning of timing belt issues, or something in the alternator. Any suggestions on what to check? Thanks!

I assume you mean serpentine belt since there's no "timing belt." Do you hear the same noise when you rev it in park? If so, find a way to listen for the source of the noise with something like a mechanic's stethoscope or even piece of a flexible hose. If not, I'm not sure what to recommend but I myself occasionally use a Chassis Ear tool.