Have a 2000 GMC Siera 2500 full 4 dr crew cab 5.7L 6.5 foot bed with a split drive shaft that vibrates from 30 to 50 mph. I have taken the shaft to a spicer machine shop/dealer and had them rebalance it but didnt solve the problem at all...within a couple hundred miles it started vibrating and shaking the whole truck again. Obviously this is why they went to the bigger diameter aluminum & fiberglass one piece shafts, but unfortunatley, GM doesnt make the oem shaft for my truck anymore. So I'm wondering do I have a machine shop make me an aluminum one piece shaft (if possible) or what to do. I dont wanna sell the trk just because of a drive shaft but this is seriously hardly driveable from 30-50... PLEASE HELP!!!!!