I have some of the ones that were listed as N/A's.
FFL: Flint, Michigan + Fisher body plant 1 BOC (Buick Olds Cadillac Plant)
TT5: Tungsten Halogen headlamps
UA1: Heavy duty battery
V73: US/ Canada (vehicle statement)
YT9: specified, division installed (Fisher) Reference to custom door + quarter buildup option code YT1
6YT: Front, driver side spring rate
8HP: LH rear spring rate
9HP: RH rear spring rate
Hope this helps out. I am also still missing descriptions of the following codes:
BMD, D3D, E7K, NK1, N90, T1Y, VO8, WA8, 6CU, 7CU, 7YT, 77E, 77I, 779, 9PZ.