Boss 429 has been sitting for 30 years because the original engine was pulled for a rebuild in the late 1980s, but the shop doing the work went out of business, and the engine disappeared (suspiciously)

 There isn’t a transmission or a correct rear end, either, and the trunk has been replaced with an incorrect one.

https://www.hagerty.com/media/auctions/rm-sothebys-2021-march-open-roads-7-barn-finds