[Mntom]

I guess it would be up to you if you want to section a piece of frame in the middle or extend what you have. Since you desire air suspension I would look for a cut off that has the air springs on it rather than try to remove your springs and bolt the air ride on. You should be able to find out about the pinion angle from your driveshaft supplier. The worst of that would be getting the right wedges. As far as I know the only rule of thumb for the length of the drive shaft is it needs to fit the wheel base. I have seen some so long that there were three carrier bearings on them.