So was this a two-door Plymouth wagon that someone mounted a DeSoto front clip on? Or was it maybe an export-only edition?
You just rubbed the right genie. Here's a six-banger for auction. Unfortunately, Chrysler's version of the Edsel is, in this case, just a shortroof: https://auktion.catawiki.de/kavels/12480313-desoto-diplomat-1959