I have a 1998 Oldsmobile Bravada auto trans drive works fine but no reverse

Likely transmission is bad--check fluid level first--using instructions on dipstick. If ok. have checked by transmission expert.

Are you sure you have all 4 forward gears? Most of the time a no reverse condition also means 1st and 3rd only.No 2nd or 4th.If you dont have all the forward gears as i suspect , the reaction shell is stripped or broken.If you do have all the forward gears then these are the two most common reasons you do not have reverse.1 reverse input clutches are damaged or burnt 2 forward cltches have slipped to the point they are welded together causing a mechanical bind in reverse and also causing the transmission to pull forward in neutral.Let me know if i can help.Good Luck.