I think the o-ring is kind of a blue color. Mine didn't come off of the intake, so it appeared as though there wasn't one there, but there was.
12 LS M6, IPF S/C, ASA GT-5 wheels, VMax PTB
1995 Mitsubishi Montero SR
1987 Dodge Raider Turbo Project
1986 Mitsubishi Montero 2.4l FI Transplant