OE fiberglass belted tires were NEW during the '68 model year & I don't know of any '68 MOPARS that had them available (maybe some Imperials and/or Chryslers? others late in the year?).
When the '69 model year rolled in - many cars had them OPTIONAL, and a few had them STANDARD (or included with an OPTION or package) - for example: they were included with the HEMI engine OPTION on b-bodies (& the ONLY available tire with the "recall" 15" wheels on a b-body).
as far as the 1969 Fury:
OPTIONAL"U24" - fiberglass-belted (GOODYEAR POLYGLAS)
G78-15 white wall
"U36" - fiberglass-belted (GOODYEAR POLYGLAS)
H78-15 white wall
"U74" - fiberglass-belted (GOODYEAR POLYGLAS)
G70-15 white streak
&
"U44" - fiberglass-belted (GOODYEAR POLYGLAS)
J78-15 white wall (station wagon)
didn't see any RWL (or "red streak") tires on the '69 Fury OPTION list