Guys, I am having a problem with my front tires "dragging" my rear tires in 4 wheel drive. I have broken u joints as well as a drive shaft. My question is "are the front and rear end gear ratios on a 1978 Jimmy the same?" Mine are not. It looks as though this may be my problem. I have a 41 tooth ring on the back with an 11 tooth pinion. On the front is a 40 tooth ring with a 13 tooth pinion. One other question, how critical is tire size. My front to back tire diameter is only 1/4 to 1/2 inch difference. Please can anyone help?