i have a 90 full size blazer. it just broke the rear pinion. i'm not sure what gearing is in there now, so i was thinking of going 4.56 or 4.10. any recommendations? it has 38.5 inch tires but they are getting old so i would go down to 36 with the right gearing or stay at 38, it doesn't matter too much. also would like to know what the o.e.m. gearing was in that truck because i have a feeling that's what is in it right now.