GM started the conversion in 1985 and everything had a one piece rear main seal and hydraulic roller lifters by 1987. As such if you look in the lifter valley you will see the stand offs cast into the valley if it has a one piece rear main seal if those stand offs are drilled and tapped it was used as a hydraulic roller. The lifter bosses are also taller on a one piece block but that is hard to determine visually.Thanks for the pictures, I will check it out. I was told by tech guy at JEGS today that the older blocks had the 2-piece and it wasn't until mid 80's did they switch to the 1-piece.
That isn't me or my picture I quickly mined it off the web.Hey Dave. You say to offset the 2 piece 15* yet the picture you posted Ike's not show it offset?