I was working in the shop when that Pinto, early in it's short life, came through Volpar for a short moment. Smolinski moved on the Goleta before the thing came apart.
Volpar lost half of management in Ensenada when Thrifty-Mart's Turboliner stovepiped after I went back to collage. That left Mr, Nixon to sell Turboliners to Air-America:(
Volpar's owner (Secretary, OX5 Club) sold me their testbed Falcon-20 (cn58) for $200 in 1994, it cost me almost $3k to get it home, I think most of the luckier Ford Pintos were still going in 1994. Gad, what a great pipe dream; a FLYing Car !
The wing spar of the Model 18 was fabricated by welding an assembly of tubular steel. The configuration of the tubes in combination with drilled holes from aftermarket STC modifications on some of these aircraft have allowed the spar to become susceptible to corrosion and cracking while in service.  This prompted the FAA to issue an Airworthiness Directive in 1975, mandating the fitting of a spar strap to some Model 18s. This led, in turn, to the retirement of a large number of STC-modified Model 18s when owners determined the aircraft were worth less than the cost of the modifications. The corrosion on unmodified spars was not a problem, and occurred due to the additional exposed surface area created through the STC hole-drilling process. Further requirements have been mandated by the FAA and other national airworthiness authorities, including regular removal of the spar strap to allow the strap to be checked for cracks and corrosion and the spar to be X-rayed . In Australia, the airworthiness authority has placed a life limit on the airframe, beyond which aircraft are not allowed to fly.