GSN never aired 1987-88 regularly or any other 80s grey hair show aside from most of season 20 plus a couple of spot episodes during Club AM/Prime Games when they first started teasing adding TPiR and later on during WinTV.
For anyone curious, GSN aired in regular run:
*Somewhere around 190 (+/- a couple) half hour Barker shows from the first three seasons. (None from S4 or the occasional one-off thereafter).
*Approximately 1/6 of the episodes from November 1975 through June 5, 1978 (had GSN not changed the way they aired TPiR in '98 when they got the Goodson shows back, it's VERY likely Finish Line would have aired on GSN in May '98)
*Approximately 1/4 of the episodes from September 1979 through June 1982 (in general, early 80s shows featured fewer furs and other issues)
*Basically all of September 1982 through February 9, 1984.
*September 1986 - February 1987
*September 1991 - April 23, 1992.
They've also aired a couple dozen misc. eps outside of that run, including but not limited to: one Spring 1979 show in WinTV (the only s7 ep they ever ran) at least one episode from April 1987 they hadn't gotten to yet, the season 14 Premiere in WinTV, the S16 finale with test Chyron credits (only lasted 1 ep) before launch, the season 18 premiere (again WinTV), several Christmas shows (1984/1990) in marathons, and at least a few 70s/early 80s episodes in WinTV from the time period they aired in the 1996-98 rotations (1975-78; 79-82) that didn't actually air normally the first go-around.
For comparison and folks not keeping score at home, the streaming offerings have included
100 shows from September 1972-January 1974 (including several episodes GSN skipped, while skipping several they aired even when no furs present)
and the vast majority of September 1982 through January 9, 1986, though streaming here HAS skipped several shows GSN ran [and aired at least a couple they'd skipped due to tape issues])
(also a note for the folks at home, the above is not an entirely comprehensive list of airs and skips nor is it intended to be to the episode. If they randomly aired a show from 1988 in WinTV I didn't account for, it's fine)