Yes, and Scott's in Penhold is a Mar-K dealer. I do not think MAr-k handles the short bed sides anymore, but I am sure Scott will have found another source.
Scott's has a webpage,
http://www.scottssupertrucks.com/ but it is not the best and he does not answer email very well. Phone them at Phone: (403) 886-5572 or 1-800-GMC-CHEV (Toll Free - Canada Only)
I purchased a complete short bed for my 59 GMC from Scott's and have talked with them about a 68-72 short bed as I am working on and driving a 69 now.
By the way, welcome from Fort Smith NT.....