Jazzyvee,
If that photo is the actual IN-2 that you bought, the 1/4" jack next to the 5-pin connector is an unknown mod.
But the IN-2 is not a complicated device and there are only a few components, as you can see in this thread:
https://club.alembic.com/index.php?topic=21890.0Basically in and out jacks, a self contained power supply, two very nice UTC audio transformers for the DI outputs, a selector switch with some summing resistors... and that's kinda it. In other words, if yours has been stored in a swamp and is badly corroded, you could completely rebuild it without spending too much money.
Quite a score! In my road trunk I'm lucky to have a collection of spare bits. Two preamp boards (one pre-tuned with RW's mod), a prewired p/u selector switch, a full set of knobs, 5-pin connectors of all variety, etc. This is why I guessed that the kit you found could only have belonged to either JE or maybe MK. That collection of rare parts might not mean much to somebody who didn't know, but for all of us in here ... just wow!
Jimmy J