I dont know about the factory ifs unit working because of the offset center. If I use jeep or toyota axles I will reinforce the housing any way and by the time you do that there wouldn't be too much of a difference in weight, I wouldn't think. Plus you would raise the pumkin up 4 inches or more. And if done right big if maybe 4 wheel steering.

87 dodge raider,2.6 33/12.50's 3 inch B/L
92 chevy silverado 350, 5 spd