I think this is a Class 11 Funko Hustler prepped by Sandmaster, raced in Arizona and Baja in the early 70s. Bobby Ferro drove it in the Mint 400, and the California 400 in 72, 73, 74

Based in North Hollywood, California, Scott McKenzie created his Sandmasters Company in the mid-to-late 1960s which provided parts and accessories for the off-road and dune buggy market.

https://www.race-dezert.com/forum/threads/rick-mears-sandmaster-buggy-arizona-1973.111876/

http://www.wagtimes.com/driverbobferro.html