The files used to be on tsx-11.mit.edu:/pub/linux/GCC
in rootdisk and
basedisk subdirectories.
There's a copy of the tsx-11 archives in the Internet Archive here,
along with 8 other archival CDs from Pacific HiTech, but it doesn't
seem to include the directories you want:
https://archive.org/details/OfficialRedHatCommercialLiNUXV3.0.3
The same item also has a copy of the old Sunsite archive on 4 CD images.
Was there a mirror of H.J. Lu's early stuff in sunsite?
Searching for "tsx-11" in the search box at the Internet Archive
turns up half a dozen (typically CDROM .ISO) images of various copies
of the tsx-11 archives.
Unfortunately, the Internet Archive never directly crawled
tsx-11.mit.edu,
seemingly because it was never accessible via http?
John