Can anybody tell me what the gear ratio is for a stock 77 Chev. 4WD truck running a T-350? I'm thinking about swapping my 89 Jimmy 10 bolt 4.56 and 6 in. lift for a 12 bolt and 4 in lift,are these springs and rear ends compatible with out any mods? Will also be swapping frt ends as well.I have measured the length of both trucks rear springs and they measure 52 in. from eye to eye.