according to my '65 NCRS judging guide:
front stabilizer bars were standard on all models but differed between SB, BB and F40 equiped cars:
Front suspension:
SB cars had a 3/4" front stabilizer bar
BB cars had a 7/8" front stabilizer bar
F40 cars had a 15/16" front stabilizer bar
Rear suspension:
BB cars had a 9/16" rear stabilizer bar
F40 equiped cars had different front shocks, rear shocks, front springs and rear spring (7-leaf vs. 9-leaf) than non-F40 cars.
The F40 suspension was only available on L84 or L78 optioned cars