I highly doubt that Shelby ordered any cars directly from DeTomaso sPa in Italy. Given A. DeTomaso's prickly nature and his long memory for those who screwed him (or attempted to). Ref. the incident when Shelby contracted with DeTomaso in 1963 to build a batch of P-5000 single-seat sports-racers, designed by Peter Brock, for a proposed FIA spec series using the 5-liter SBF. The prototype was a disaster- DeTomaso's Italian builders couldn't read Peter's SAE measurements so instead of hiring a translator, they 'winged it' and a human being couldn't fit in the completed machine. Shelby refused to pay for an undrivable car & it was scrapped.
Peter Brock was sent over to Modena shortly after and the first successful P-5000 was 98% completed by Carrozeria Fantuzzi only a few hundred feet with a second not far behind when Shelby abruptly called Peter back to California and rescinded payment-again- sticking DeTomaso with the bill for the two P-5000s (plus the prototype). The single 'P-7' sports racer was either built years later under shadowy circumstances or simply renamed. The spine-frame chassis of Brock's P-5000 became the chassis used- along with an unused prototype Ghia coupe body- as the '65 Mangusta. It was so named because DeTomaso hoped to run Mangustas against Shelby's Cobras in International sportscar competition. Then the FIA cancelled that racing class.
Shelby used the Ford money intended for the P-5000 Sports Racers to supplement his Cobra program and they won the World Sportscar Championship that year- earning DeTomaso's undying dislike. Then along came the GT-40..... All this would make a good reality TV series today, 50 years later and all the principals deceased.