thanks for the reply Kevin. There are 2 PCB's that are held together with standoffs Similarly held together in a fashion like a Neve VR. one PCB is 2086-185A and the other PCB is 2086-182A
Looks like a rebuild of a 528C input module to allow for more echo sends with level controls. He did some of this for HenryO studios. This happened before the newer API legacy boards were made. Brent would put two 24 channel 2488's together to get 48 or more inputs. The normal buss outs 1 to 8 would be used for the echo sends with added level controls. As you know the old 528C had one or two level controls and four switches for echo send.
Yeas, looks like it is based on a 515 module. I have some here that were bought as spare part donors. Unfortunately, before I joined, they were kept in a basement and got very damp, rendering them useless! :'(