68 dart sway bars?

Yeh. They did. If you try and adapt a used one you must be careful. AT the change in K members, 73/ later the bar was bent different and went inside the hollow K

72/ earlier went under the K

The tabs on the lower arms are different 72 earlier, and 73/ later

Hotchkiss and PST both offer aftermarket kits, I don't know who else

Anti-sway bar is a VERY desirable feature.