[William]

As of the 1968 model year Chevrolet dealers were no longer free to swap or modify engines.

CDSIB 68-I-4 "Dealer Modification of Air Pollution Control Equipped Motor Vehicles" was sent to all dealers. I'm sure some blew it off but smart dealers knew the consequences. That's probably why Yenko formed Yenko Sportscars Inc and Baldwin Chevrolet had Motion Performance do the mods. Gibb sent cars to Dick Harrell.

As for Dale Chevrolet, the only known "Dale Duster" around here [10 miles from Dale] is an Ivy Gold '68 Nova SS that has been red most of its life. Has had a 427 as long as I have known of it. When I was with Camaro Parts Exchange one of our customers claimed to have a white/auto '69 Duster that was little more than a roller. Never saw the car or the paperwork.

Dale was a Yenko dealer for the 1970 model year. Yunker in Oconomowoc was the closest for '69. I have said it before but it bears repeating: Dale had a tremendous inventory of HP Chevs: COPOs, L78s, JL-8s, you name it.

As for the '72, the claim is hot air until it can be proven.