I got a Chevy 12 Bolt rear end that I want to put under my 84 Cutlass. Can anyone tell me what it came out of? It measures 58 inches from the tip of one axle tube to the other. The letters/numbers I see on the case are "CONI" (lower left), "J108" (lower right), and it has line 1 "1 2 3 4 5" line 2 "6 7 8 9 0" on it. Thanks