[bigblockv6]

Lewis, the 478M finally got fired up on this last President's day, after getting things dialed in like the valve lash and timing the engine sounds great, it's good to hear it running after some 16 years and the 478 does sound somewhat different from the 305. I have yet to finish the power steering conversion before I get the truck on the road, working 6 days a week is making things difficult at this time but hopefully next month will be better. As far as the 4 ring piston issue, what I was talking about was in the early seventies GMC issued a service bulletin that stated 3 ring 305 pistons were discontinued as a replacement part. From that point the 4 ring 305C pistons were to be used in prior 305A,D and E engines for replacement and the purpose was for standardization. This all made sense at the time since only 305C engines were in production. Of course aftermarket suppliers more than likely offered the 3 ring piston.