I think he meant that the 440 4 bbl was not offered in the 72 rr and if you had one it was a gtx option on the 72 rr. The 340 and the 400 were both equipped with the 4 bbl. The Petty blue 72 rr that was on ebay had to be the gtx option as it had the 440, but he said i was a very rare rr. I am not sure if the gtx option in 72 was a code on the fender tag like the rr option on the volare but would make sense to be coded like that.