I don't remember the Monkeemobile having leaf springs. In the mid 1970s there was a tent at the South Dakota State fair with a Monkeemobile and the Boot Hill express plus several other show cars. The owner said he had run the Boot Hill Express 110mph though a quarter mile.
He priced the Monkeemobile at $14,000 to me.
He was getting tired of setting up then moving the display around the country and wanted out.