rear end replacment

Hello dually form i jave a 1999 3500 4 dr dually want to put 22 semis on ...want to start with the rear end ..any body tell me how to tuck them in ?? I heard change rear end to a 3/4 ton rear ? If so what year rear end??

It wouldn't be a 3/4 rearend you want, but a cab & chassis rearend. The 3/4 ton parts narrow your front track width. A new rearend isn't necessary tho, you can fiberglass the hips wider.