For what its worth to you, I cut down a drive shaft out of '87 D250 for my '70. It measured 4" as well, I have no clearance issues, I'm running a 8.8 rear too. The rear has been cut down on drivers side in which moves the pinion towards the drivers side. Hope this helps.
thanks, the only place i would be worried about would be at the end of the tail shaft. seems it's real tight there. think i'll put it up on the lift and hold the shaft up there and see how much room i have. dave.
