I found a similar one (maybe even the same photo) online at http://www.milestonemotorcyclerestoration.com/products. They note that it is a 1937 Harley Davidson ULH 80 cu. in. Very cool.

Really great restoration of a H-D knucklehead hardtail. Really like the springer front ends on these beauties. Late 1940's or early 1950's??