Is it possible to get a duty station at FT Buchanan as an AD 88M SSG?

Probably. If you do, it's an AC/RC slot. Plus, it's OCONUS so the person holding that position isn't moving for three years. I had a buddy who's a 92W who went two years ago. He begged his branch to get that spot. A year later he was begging to leave.
The chance of you being eligible to move at the same time the person who's there, plus your KD time complete, plus being the best choice for the position(NCOERs, schools, etc) is very slim. You can look on FMSWEB to see the unit MTOE. There's probably one AD 88M3/4 there.

Extremely doubtful as a Regular Army soldier. Ft Buchanan is a Reserve Enclave. You may have a better chance as an AGR or Reservist.

With a few exceptions it is a career killer! Plus not a lot of possibilities.