Thanks for the help Leo. According to the owner the front half of the frame is original and the rear half is Peterbilt that was welded to the original. I've done searches, but haven't found any real info on this cab as far as tilting. I found an article by an owner of one of these that said that you accessed the engine by swinging out the fenders.
So, did they all tilt or only the later ones, or were some converted to tilt like the Bullnose KW? This one looks like the back of the cab is bolted down:
IMG_1566 by Brian Smith, on Flickr
On the ones that tilt, does the grill tilt as well or does it stay.
The one in the photo has an Iron Lung Cummins in it. I'm planning a build of one of these and I have an Iron Lung Cummins, but I don't want to waste it if it's going to be hid under a cab that doesn't tilt.
Thanks again for all of the help.