Update: the problem was the Gen 2 cable not working with some '99's.
After a couple months of back and forth with Durametric, I finally got them to send me some weird hybrid cable. It looks like a Gen 1 cable (using their identification method), but works with version 6 software.
I'm now able to access all modules
Airbag light off, cluster OBC activated...I'm pretty happy.
I really appreciate Durametric's help with this, but I wish they hadn't pretended to not know about the '99 issue for so long. If anyone else has trouble with the cable connecting to the earlier models, it is a known issue for them...don't get yanked around for 2 months testing K lines.
