does anyone know if these jacks are factory?

[Enochiankey]

a friend of mine has a 1979 Marshall JMP MK2 100w head
it has 2 speaker jacks and 2 other jacks on the back and i'm not for sure what their for one of them i believe is a DI
does anyone know what they might be and if the JMP came from the factory with 4 jacks on the back
any info would be greatly appreciated
Thanks in advance

[JerryP]

Re: does anyone know if these jacks are factory?

I think it only came with 2 speaker jacks. I don't think the DI was added till the JCM800's. If I had to guess I'd say they are the send and return for an effects loop. Have a tech look at it if your not sure.
Jerry