new guy needing help

[89blacksub]

i just got my burban about 3 weeks ago in oregon and got it all the way down to texas without any problems. then the next day the rear end went out. my question is how to read the option codes in the glovebox. or if anyone knows what the stock rear would be since it has to match with the front. its an 89 4X4 1500. its got the 350 TBI and as far as i know it is all stock. i really want to get this thing back on the road so i can stop driving my wifes car (its got friggin stickers all over it!!) PLEASE help me.