Speaking of dummy loads:
http://www.brianroth.com/library/dummy1.jpg http://www.brianroth.com/library/dummy2.jpg
Eons ago (hmmm...the Dale has an 1981 date code, and I bought them new), I built up four of these. The heatsinks came from a local surplus store, and a machinist friend did the "carving" of the fins to allow the mounting legs to fit.
I had planned to mount the set of four into some sort of enclosure with fan cooling, but never got around to that part of the project.
Best,
Bri