I was just curious about the differences in these two? Also is there any place that you can find the date of manufacture from the serial number for these cameras.
There are cosmetic changes externally the main one being the wind on lever.
Internally the OM1n (and the OM2n) had a check light when a T-series flashgun was mounted in the hot shoe. It confirmed exposure was "correct" or not and when the flash was fully charged ready for the next exposure.
The OM1n was introduced in the UK during summer of 1979. The OM1 was phased out during 1979 after stocks were sold off. I had a hard time finding an OM1 during this period because most outlets were sold out and awaiting delivery of the OM1n.
I don't think Olympus ever kept a running list of what serial number went to what body (or lens) and in what time frame like Leica did. A serial number range from say, 600,000 to 700,000 could cover several lens or body types over time. 600,001 could be a 50mm lens and 600,010 could be a 35mm lens assembled on the same day. At least that's what I've been told.
From reading about the OM 1/OM 1n history it seems that there constant internal improvements throughout the production run i.e. in addition to the flash ready light. That would make me favour the OM 1n over the OM 1 although what those improvements may have been I have no idea.
I'm sure Olympus claimed improvements to the durability of the shutter and winding mechanism too with the introduction of the OM-1n.
The OM1-n also takes a completely different flash adapter. It threads on with normal right-hand threads. The OM1 takes the Shoe-1 which threads left-handed. Shoe-4 is probably more easily sourced and seems less likely to crack. The OM1-n also seems to have less problems with decaying foam eating into the prism coating.
The very early OM1 had a different eye piece and some internal wiring was not as good as the later models. But it seems to me the early ones had better advance gears.
There are more knowledgeable people than me about these facts. I have 3 OM1's right now and 1 OM1-n. They're all great but I prefer the OM1 -- it just feels silkier.
The very first OM-1 was actually labelled an M-1, until Leica complained.
Then the camera's name was changed to the OM-1. The original OM-1s required a factory modification to permit use with the motor drive. That modification was surprisingly popular, so within about a year all new OM-1s started coming pre-modified, and with the designation OM-1 MD. Almost all of the OM-1s you will find that are not an OM-1n will actually be OM-1 MDs