So I'm doing some archaeology with my collection, and have noted a couple perhaps not surprising oddities with my hardware.
Firstly I have a Rev 4 mainboard, and I haven't found any information about this particular revision anywhere. It claims to be a 'W.C. Build' from March 1987, and has what I'll refer to as 'high quality' RCA connectors. That is they are color coded Red/White/Yellow with a plastic insert, as opposed to the cheaper looking rust colored inserts on most of my other machines. This is currently sitting in a standard A500 case w/standard keyboard, but those may not be original.
Secondly I have two Rev 5 machines, based on pictures at BBOAH both appear to be the 'Type 4' mainboards.
If my suspicion that the silk screened label reading '1298A 23--87' refers to a manufacturing date, than the older of these machines also has the same high quality RCA connectors as above, but also has a keyboard with a a C= key in place of the left Amiga key, and the C= logo is part of the case casting, as opposed to a sticker on my other machines. This machines also has a metal cross bar running diagonally across the Agnus socket, and the top shielding was not made with a removable section over the CPU as in later machines. Finally this machine has the number 24 hand written on the yellow serial number sticker.
The newer machine, i.e. '1298A 19--88', has the lower quality RCA jacks, No cross bar on the Agnus, and the more common keyboard and case. The shielding in this case has a removable section over the CPU.
I'm not particularly interested in the 'newer' Rev5, as it meets all my expectations and memory of what a Rev5 A500 looks like, the older one is a different matter. My original plan was to use the Rev5 machines as parts for my workhorse Rev6a, but now I'm having second thoughts, at least for the 'older' machine.
As for the Rev4 mainboard. I can't find any information on it, perhaps some one out there has some.