I'll see if I can find some pics. If memory serves correctly 339A had the brass things on the u bolt and the 341B did not.
Just come across this on the samba.com http://www.thesamba.com/vw/forum/viewtopic.php?t=492528&highlight=hinge unit The last post in the thread lists some differences but makes the point that any complete unit will fit any Bus.
The U hinge is certainly different as I've tried to assemble a wrong one and you can't. The one with the bushes is longer on account of the bushes sticking out top and bottom.
