I thought so too, but I printed out a copy of a sales brochure from 1969 lists the front sway bar as an option, unless you got a 340, 383 or a trailer towing package. However, it looks like you could order the heavy duty suspension package on any model. As written in the brochure:
"Suspension, heavy duty-std with 340 and 383 engs, and trailer towing packages. Includes H.D. torsion bars, H.D rear springs, and , and front anti-sway bar. (H.D. shock absorbers are avail. with this option)."
