[bigblockv6]

Nothing that I heard of but in 73 the whole line of V6 engines other than the 305(the 305 originally was slated to be discontinued for 72 but they decided to keep it going) went through upgrades. The gas engines only used 2 bolt main yet the Diesel versions had 4 bolt mains, actually cross bolt mains. Possibly there may have been some bottom end failures with 478's in the 7500-8500 series trucks, I have a 73 478M and the main caps are so much larger and contour better with the bottom of the block. I'll takes some pics of both the new style caps and old caps for a comparison and post them sometime this week.