Im reassembling my 7.4L HP 450 (after the Gen V block was overheated and cracked) Upgraded to Gen VI block and was wondering if there was any reason for not using the oil passage o-ring between the #5 bearing cap and block.
The only reason I ask is when I disassembled the old block the o-ring was missing. Is this normal or did some one forget to install it last overhaul.
Thanks for any help.

I'd say someone forgot it. It's inexpensive, put it back in.

The oring is supposed to be installed. Go ahead and put it back correctly.

Talk about fast service.......not even 20 minutes for a reply!
Sounds good to me. The only reason I could have thought not to put it in would be if it deteriorated or broke it could make it's way through the oil system and get stuck somewhere important!
Thanks for the info.

Oring comes in the pack with the genv/vi 1 piece rear main seal.