My LATCH manual doesn't list details for pre-2001 model year GMs at all and I can't say for certain. The 2001 Montanas are listed with full LATCH (lower anchors plus tether anchors) in one or both of the second row outboard seats, depending on the type of second row vehicle seats. The '01 model is listed as having no lower anchors in the third row, but has one or more third row tether anchors depending on the type of vehicle seats in the third row. I'm not certain if this would also be true for the '00 model year Montana, though. The '00 model's owner's manual or another '00 Montana owner could help clarify.