• by David Goetzl  @dgoetzl, May 26, 2011

Cadillac is backing a season finale stunt on Discovery Channel's "American Chopper: Senior Vs. Junior," where actual choppers will be auctioned online and the proceeds will go to charity.

A two-part season finale (May 30 and June 6) will feature a competition between father and son, Paul Sr. and Paul Jr. Teutel, competing to design a custom motorcycle "inspired by Cadillac." The father and son pair met with Cadillac design and technology experts in preparation.

The bikes will be the subject of the online auction at discovery.com with the funds going to muscular dystrophy charity Cure Duchenne, which is backed by Cadillac.

Set in Newburgh, N.Y., "American Chopper" started on Discovery, then moved to TLC, before returning last year. Discovery said a crossover episode Monday with "Deadliest Catch" was the top-rated non-sports cable program among males in the 18-to-49 and 25-to-54 demo.

The show has 452,000-plus Facebook followers, which pales beside the 1.85 million for "Deadliest Catch."

Maker's Mark is one of the advertisers on the "American Chopper" home page as it commits its full 2011 TV and ad budget to Discovery Channel.