NHRA put the Kabosh on the Porsche seats. The test mule served the purpose of seeing what would be allowed by NHRA In addition to evaluating performance. They floated the idea, NHRA said no. Makes sense if you consider that Porsche seats aren’t really a Chrysler end product not even a US end product. The cut wheel wells was a mod to an existing body when it left the factory/shop it became a factory body. no different than the nose and wing being added to a roadrunner to make a Superbird. As far as odd parts the only other non Chrysler parts were the Headers from Hooker, Corning glass and the Hurst shifters. Everything else was production Chrysler parts. The Corning glass had been used in the 64-65 cars so it had a precedent, the shifters were dual gates used in GTO’s. Porsche seats were too much of a stretch. You could argue that the glass fenders and hoods were non production but they were assigned a Chrysler part number, the A990 lightweights had aluminum fenders and hoods made by outside vendors so again there was a precedent. The Dart and Cudas essentially ended up being A Body versions of the A990 cars. The real advantage was weight. The use of outside construction and vendors is still in use today the shaker challengers go to a vendor for the shaker install it’s not done at the factory assembly line.