Hi, I have a 4.56 gear in my 85 and want to swap out to the rear end of an 89 complete rear, rotor to rotor. Both are dana 44. I have read that there are problems with different mounting locations for some of the bolt on parts of the 89 rear end into the 85. I am doing this for two reasons. The 89 has taller gears,that is numberically smaller, and I believe the 89 has substantially lighter springs both items of which will be quite a relief for gas mileage and ride of car. I believe the rear of the 85 has a z51 spring so there should be quite a drifference. Also, will it require mods to the front springs stiffness wise if this is done. Thanks for any input.