I actually read somewhere that Zero pilots could switch some gauges by personal preference, and historical pictures seem to back this from what I've seen. Or perhaps depending on the manufacturer they were just different I'm not quite sure.
As far as production, I'm not really sure myself. Although I've seen rough estimates on total Zeroes produced during certain times, it isn't specific on the model. Here's what I've got anyways....
Mitsubishi Nakajima Total
Mar 1939-Mar 1942 722 115 837
Apr 1942-Mar 1943 729 960 1,689
Apr 1943-Mar 1944 1,164 2,268 3,432
Apr 1944-Mar 1945 1,145 2,342 3,487
Apr 1945-Aug 1945 119 885 1,004
Total 3,879 6,570 10,449
Anyways, can't help but feel like were hijacking this thread so much to my displeasure I'll stop here.