i have a 99 dodge ram rear end and i can't find the tag on it and would like to know what type of rear end would it be , it has a 12 bolt hole cover on it and i understand they offered a 8.25 and a 9.25 and i believe another type also not so sure.. but the one in the truck has 12 bolt cover and it is a 5.9 engine with auto trans ..thanks guys

9 1/4" rear with 3.55 gear or maybe 3.91.

thanks so much , i kinda figured on it being a 9.25

Make sure it has fresh gear oil, and keep it topped off and changed every 20K or so. The 9.25's are known for issues. I've owned 4 ramchargers over the years, and one currently. Two had noisy 'whiney' 9.25 rears. I rebuilt the rear in my current one last year do to grind & whine.

I had a whining noise in my 98 Ram's 9.25 for a couple of years before I fixed it.The inner pinion bearing's race had a lot of pitting.A couple of bearings later and all was good,I hear it is pretty common on them.
Keith

8 1/4 Round (almost)
9 1/4 Stop sign shaped