I am in search of a FS5W63A transmission or gears for this transmission, or if anyone can tell me what other transmissions would be compatible with a 1982 200sx (or other years or models that would have a match). I know this forum is for 1200 but I am hoping there are fanatics out there that can give me a hand. My son inherited his grandfather's car but we can't get it running because we can't find the parts.

Was used by 1977-1979 200SX. Newer 200SX uses a.stronger more common transmission

Which parts do you need?
180B, and 910 5 speeds should use the same parts.
I repaired an A series 63A five speed using parts from a common as much L4 four speed box.

Mixing and matching may work but what to be aware of is the number as the 63 in this instance means 63mm between centres of the two gearbox shafts.
therefore an A series has type 56 and 60 gearboxes datsun 1600 and 180B were 63 as is yours and the six cylinders and some later 4 cylinders FJ20 etc were 71 type boxes.
So the number being the spacing between the shafts gives you an idea of the dimensions of the geard, However while some interchanges can be made it is not always a given but is a starting point.

Type 63A 5 speed was 200B SSS, 180B SSS, Stanza(Violet) including GX and SSS as well as some homemarket models like some Laurels and Bluebirds.

63A 5-speed for USA market was in 1977-1979 200SX and 1976-1978 B210.

The 71-series 5-speed was used by most Datsuns including 1980-1982 200SX, they are a dime a dozen and far stronger than the 63-series.