This thread is a little dated but I thought I'd post a follow up. I was at Classic Parts for the KC Chevy/GMC truck club meeting the other day and picked up some door rubber for my clam shell doors. On closer inspection I found the the perimeter of the upper and lower doors had holes drilled for the rubber seal clips just like the driver/passenger doors. On a hunch I had them give me a front door rubber set and I test fitted it on the clam shell. Fit like a charm. I bought the kit and installed it the next day. It works great. The clam shell doors are slightly smaller in circumference so I had to trim the ends to fit. I put a little weather strip adhesive at the seam and it looks quite nice. It helps out tremendously with rattle/road noise and exhaust fumes.
So, although it is not marketed for the the clam shell doors, the Classic Parts #03-012 "(1955-59) Door Rubber Seals - Clip on - pair" works like a charm.
I assume it would work on barn doors as well.
