I had a VYII SS Crewman which had front and side airbags. I recently purchased a VZ SSZ Crewman but it only has front airbags. As the SSZ is better equipped than the VY, I wonder why it doesn't have the side SRS option. The differences are that the VY was an auto and the VZ is a manual.....
A VZ SSZ should have side airbags from the info i can find. Perhaps the B pillar stickers are missing? Squeeze the upper bolster of the seat, it should have something hard (the airbag) in it. Also there should be a yellow wiring loom coming out of the seat.
Check your vin number and look inside the owners manual, it explains all the number codes, and will tell you what safety level pack your car has
Quite possible it was still an option at the time? I know the standard ute doesn't have side air bags.