[69L78]

I just talked with Kelsey Tire and they told me they were originally used on B body cars the first half of 69, on GM mid size cars like the 71 Chevelle SS, and for a warranty replacement for the 68-72 Corvette because they were more readily available, and also he did suspect that they were used for a replacement warranty on the Z/28, because they were more readily available than the E70-15. I am no expert, so here is the phone # for Kelsey Tire. 800-325-0091