I have a 98 z28, do I need to buy an install kit with my Richmondring and pinion?

 

Yes you do. What's usually included is the following:
Ring gear bolts & washers, crush sleeve, pinion carrier bearings, pinion nut & washer, pinion seal, marking compound & brush, thread locking compound, silicone sealer, pinion & carrier shims, cover Gasket. You DO NOT want to reuse any of those old parts, some for obvious reasons. The one thing you could do without is the cover gasket. I only use the silicone gasket goop and forget about fighting with the gasket, it won't leak.I have to ask though, since you asked that question, do you have the knowledge and proper tools to set-up the gears correctly? If you don't set them up properly with the correct mesh and backlash, you'll end up eating the gears sooner than later.

 

I'm going to take it to a mechanic.