A pair of historic Mopar convertibles will be among the featured lots at Mecum Auctions' upcoming sale in Kissimmee, Florida.

Offered as a set, the 1970 Dodge Challenger R/T convertible and 1970 Plymouth 'Cuda convertible are very early pilot production cars. That makes them among the first examples of the Chrysler E-Body platform, which debuted for the 1970 model year underpinning the first-generation Challenger and second-generation Plymouth Barracuda (sportier versions got the shortened 'Cuda name).

1970 Dodge Challenger convertible pilot car (photo via Mecum Auctions)

1970 Dodge Challenger convertible pilot car (photo via Mecum Auctions)

 

The cars up for auction are believed to be the second Challenger convertible built and the first E-Body Barracuda convertible. Both are also claimed to be the first E-Body convertibles built with the legendary  440-cubic-inch "Six Pack" V-8, named for its trio of Holley two-barrel carburetors. Both cars also feature 4-speed manual transmissions.

Both builds are rare. Dodge only offered the R/T grade and the Six Pack engine for the 1970 and 1971 model years, and R/T convertibles were only available for 1970. Mecum estimates that just 61 were built with the Six Pack engine. The 'Cuda convertible is believed to be one of just 16 1970 models built with the Six Pack engine and manual transmission—and the car up for auction is claimed to be one of just two painted white.

 

1970 Plymouth 'Cuda convertible pilot car (photo via Mecum Auctions)

1970 Plymouth 'Cuda convertible pilot car (photo via Mecum Auctions)

The pair of convertibles are even more noteworthy because they're early-build pilot cars rather than regular production models. Pilot cars are among the first examples of a given model, built to iron out any issues with the production process. They're sometimes used for media test drives (which was reportedly the case for the Challenger) but generally aren't offered for sale to the general public.

Mecum expects the convertible duo to sell for between $750,000 to $900,000 at auction. That's a testament to the pair's rarity, but also the fact that the 426-cubic-inch Hemi V-8 is still more valued by collectors. Hemi 'Cuda convertibles have fetched millions at auctions in the past, and Mecum has an example that it expects to sell for $2.5 million to $3 million at the same Florida auction as the pilot cars.