The front axle from the Grand will need the spring perches moved in 1/2" per side. On the diff side there is typically enough room to redrill the center pin 1/2" closer to the diff. You may need to grind a little of the webbing away around the diff, but it is nothing major. On the pass. side, most I have seen simply weld a piece of 1/2" thick steel to the inner side of the spring perch and redrill the center pin hole 1/2" further in.
THe grand axle CAN be bolted in directly, but it is pretty hard on the leafs being spread like that.
The pinion bearing WILL NOT oil properly if run upside down and will quickly grenade.