Hello Jochen,
the 0237 was one of four JU 86 Z-7 flown by the "Lloyd Aéreo Boliviano":
860013 Illimani
860234 Mariscal Santa Cruz
860237 General Perez
860240 Mariscal Sucre.
Codes are not known.
Details are in the website
www.lloydaereobolivianofriends.com
Regards
Leo