mustang with a straight 6?

Correct Craft definitely installed some straight 6's in Mustangs. I've seen several Chrysler slant 6 engines and I know Interceptor sold a Ford straight 6 which this one probably is. You can attempt to narrow down model years by the different top deck configurations and different gauge clusters used. Most pre-65's I've seen had the gauges lined up across the dash. 66-68's mostly had the non-squared metal cluster, and the 69-70's had the rectangular simulated wood grain cluster. Most 66's-up had the molded-in scoop on the front deck with the two front vents and the 68-70 models have the additional awkward(sp) chrome scoop mounted on top of the molded scoop. But CC did alot of unique things over the years, and the 6 cyl model I have photos of had no vents in the molded scoop at all and a chrome scoop off to the side. And of course if you can get the serial number off the stringer or inner gunwhale, then CC can tell you everything.
-Reid