I saw on the neck plate that it was made in 1981. 1981 ST80s are two piece bodies as specified in catalog. I believe 1980 and earlier ones are one-piece bodies. I do believe a 1981 ST100 had a flamed neck. And yes, there are ST100s with nickel hardware. But Its probability being an ST 50 is much...
It's probably a 1981 ST 50. The 60 and 80 are two-piece bodies but I can't find any seam in the middle of the body. 1981 ST 100 would have a flame top and gold hardware.
I'll ask for more details. So far I guess the model would fall in 1981 ‘64 st50-80 or 1982 '64 st50, 60, 80. It does not have a slab fretboard so it must be a '64 model.