I had the same problem finding ones for my Gassers. I have never checked it, but the M37 panel is real close. Some very helpfull fellow members sent me the ones I have now.
Are you wanting to make a restoration or a driving truck? I ask because if you took a multifuel dash panel and bolted it into a Gasser cab (yes, it will bolt in) you could then use a multifuel gauge panel. I didn't do that and kind of wish that I had because I hate not having a tach now that I am driving the truck a lot. The OA331 needs to be driven hard to get you anywhere. I use about 2 mph below the max speeds on the data plate as my shift point for each gear. 8, 14, 25, 42. I have no clue what rpm that is though.