Thanks for reaching out. Our website doesn't list a lot of pre-1980 models simply because we haven't had time to add them, even though the bulbs will fit in many cases.
With your GTO (one of my all-time favorite muscle cars, by the way), I'd recommend looking up the stock bulb size, and either giving us a call at 314-205-3033 Monday-Friday 9 a.m.- 5 p.m. CST, or shooting us an email at [email protected]
. Our service team will be able to tell you right away if we offer a compatible replacement!
Thanks Mike, let me know if any other questions come up!