Welcome!! Nice Panel
If you have the serial number, you can plug it in here:
http://www.t137.com/registry/help/decode.php
The engine should have a serial number stamped on the
side of the head above the generator. The '50 motor would
have started with T-172*******
http://www.t137.com/registry/help/otherengines/tengines.html
Both Roberts and Bernbaum are forum sponsors:
http://www.robertsmotorparts.com/store/trucks
http://www.oldmoparts.com/parts.aspx
More vendors:
http://www.dodgecentralmi.com/ocart/
http://www.steelerubber.com/
http://www.pilothouseinteriors.com/
A great reference book:
http://www.amazon.com/Dodge-B-Series-Trucks-Restorers-Collectors/dp/1583880879
More knowledge:
http://dodgepilothouseclub.com/know/know.htm