Can anyone please tell me about this serial number P 136 B. I purchaced this instrument in 1985 new. There is no din connector except for the cassette dump. 
Not sure what you’re asking.
If you mean your Moog Source doesn’t have a MIDI jack, that’s normal.
It was designed just before MIDI and didn’t come with it.
Sorry for the ambiguity. I understand that when Moog Released a new product they sent the first one out with a serial number of 1001 and so on. My serial number is P 135 B. What is this odd serial number about?
Well if you bought a new 1985 Source, I’d guess the P B stands for Post Bankruptcy.
(I really don’t know.)