This is a Jacobs after-market pre-amplifier for a crystal pick-up.
It was most often used on models 1015 and 1080 when converted to 45 rpm or a lighter tracking tone-arm.
I believe that it can be used with any model however that has a 6L6 tube in the amplifier.

I have scanned and posted the Wurlitzer Kit 87 schematic and installation instructions below the photos.
They may be helpful as a guide line for installing this Jacobs pre-amplifier.

This pre-amplifier has not been tested or restored.
The 6J5 tube is not included.

I do not know if the Jacobs pre-amp is the same electrically as the Kit 87 pre-amp.