Finally got the truck done and all I can say is she runs GREAT. My tuner would only do a 2nd gear pull due to 2 piece steel drive shaft. He said the trucks with this driveline are governed from GM at 100mph and did not want to be responsible for damage. Pulled to only 4800 rpm and made 348hp 331 torque. We pulled to 100mph in 3rd and he wanted to stay in 2nd and word to 6200. I went with .040 gaskets and .060 off heads to get 57cc. wish I would of gone .100 honestly. Thats over 100hp gain from stock. I was disappointed in the replies that I got from here earlier this year. 11.17:1 compression 5.3 turned out pretty good with cam and exhaust and everything else stock GM parts. Tuner said sure its 5.3 ? Old school thinking and trusting your gut for the win! I did balance rotating assembly using Gen 4 rods [used] and new GM flattops.

 

the two piece shafts are fine, they have a much higher critical speed than the one piece aluminum