Thanks all.
I did join the axishistory forum and asked there. You were all on the right track. Seems there is an older style caricature on the larger plate. It says rectifier tube on off switch. The other two are – 37A low-frequency two-stage or two-step, two-level. The third says To oil pump.
The guy who gave them to me said his Father mentioned they were off a A6M Zero. He has a larger plate from the outside of the aircraft. He just needs to locate it!
Here’s a direct link to my request and answer.
http://forum.axishistory.com/viewtopic.php?p=1881141#p1881141
Regards, Stephen.