Unusual Altair 8800 power supply. Upgrade kit, factory error, or something else?

[Tom Moss]

Hi All,

I have what appears to be an Altair 8800 with the original Rev 0 front
panel, but the rear panel and PSU is a back-to-front version of what's
standard on the 8800b.

Pictures at http://imgur.com/a/2EVRS

I'm guessing this is a factory error, since the bare patch for the bridge
rectifier and case holes are inverted too. But I'm aware of an upgrade kit
(8800b-PS) that was offered to 8800 owners. So I'm guessing that's where
the PSU and panel came from.

Can anyone shed some light on this? Are there others like it?

Regards,
-Tom