I've got a '71 GMC 6500 with the 427-5 speed, 2 speed rear combo that is set for hauling a GN trailer. It's just about ready to start earning it's keep around here. I'm really curious how it's going to do on gas mileage.
http://67-72chevytrucks.com/vboard/showthread.php?t=306565&page=10 post #245 is mine.