The cn is as quoted by the FAA but that is questionable as it relates to a Bucker built machine when this is a CASA built one

This Jungmeister originally belonged to Spanish aviator Col. José Luis Aresti Aguire. In the middle 1960's it was found in an aircraft junkyard in Spain by aerobatic pilot Mike Murphy. He bought it from Aguire and shipped it to the USA. It was rebuilt during 1966-67 where the 160hp Siemens-Bramo Sh 14A engine was replaced with a 185hp Warner Super Scarab engine. It flew again 26 July 1967. On 5 May 1973 it was handed over the EAA Museum. This aircraft is normally given as a Dornier-built Bü-133 with cn 31 but that is incorrect as that was still HB-MKE when that crashed in 1972 in Switzerland. This must be a CASA 1.133L, but the real c/n is not known.