A parts-bin special, the 1970 Mustang Quarter Horse, also known as the Composite Mustang, featured a Boss 429 body shell married to the underutilized Shelby front doghouse, a Cougar dash assembly, and a 428 CID Cobra Jet engine. Two proof-of-concept vehicles were built: this Grabber Blue example and the snappy red job in the lead photo at the top of this page. Both cars survived and reside in private collections, reportedly.