Street, bomber V8, 6 and 4 cyl and the 4 banger class when equipped with a 2.3.
Poor year model car design for dirt racing. Bad suspension grade.
The 79-93 are better designed with better suspension and better up grades.
I've seen a couple 65-66's with an inline 300 6 cyl do fairly well against the V8's in the same class's.
Not enough Fords in dirt tracking anymore unless it's 4 bangers.