did some poking around on rockauto ;
late T2.5 TI have a
FPR that looks like the buick grand national which looks like the accufab
and as yu suggest there IS an o-ring listed separately, as "fuel rail o-ring kit"
theres a kit with 2 O-rings $2.50
STANDARD MOTOR PRODUCTS Part # SK18
also just a single O-ring is available
ACDELCO Part # 19258137 {#22516256}
SEAL,FUEL RTN PIPE (O RING) 6.07MM ID X 1.30MM THK
for $0.52 lol; with a LARGE interchange (All GM) so should be eZ to find... YAY
also list DORMAN Part # 55180
'fuel line repair' kit including 6" of steel line, threaded nut & o-ring $7