Cleatus- Don't weld the diff! You will need it working in order to turn sharply without one tire skidding, remember the rear axle will track a smaller circle than the front so you need a "transfer case" that will allow the speed difference. Otherwise it will be like trying to drive an older "part-time" 4x4 on pavement with the four wheel drive engaged as opposed to the more modern(?) full time 4x4s....You should be able to use a different gear ratio in the two axles as the fierro diff will allow the speed difference. Just use the wheel brakes as a "Posi -Trac" by way of two separate brake pedals-left front and right rear on one, right front and left rear on the other. This will solve high centering problems on rough ground but won't help if one side is in the mushy stuff
