In 1935, the Ford Motor Company and Pittsburgh-based Allegheny Ludlum Steel joined to build six 1936 Ford Deluxe sedans out of stainless steel. Part publicity stunt and part advertisement, the six cars were to be driven for 200,000 miles over 10 years to prove the durability of stainless steel. The idea was a success, with the cars going through multiple motors and other parts long before the stainless even thought about giving out. The two companies collaborated again in 1960 on two Thunderbirds and finally on three 1967 Lincoln Conentintal convertible. Now the trio is together and up for auction as one lot, with one of each of the cars represented. A fascinating look at something that will never be done again, these three cars should easily see a seven-figure bid at auction.