Grindind in rear end 99 GMC Sierra

Lately when I go over some bumbs the rear end in my truck grinds, I think it might be the spyder gear because my wifes went in her Yukon at 95000 and I have 99000. It doesnt do it all the time and other than that it seems fine

The first thing I would do is to remove the driveshaft and grease the slip yoke. When they dry out, the driveshaft can’t slide in and out of the transmission tailshaft correctly when going over bumps or during hard accel/deceleration. It’s easy and a known source of problems.

I am mechanicly inclined(changed the u joints), but not up on the names. Is that the splined part

Yep, the splined part on the front of the driveshaft.