This might not be the catch of the day, but at least a 386 mainboard I hadn´t come across until today.
I had to adjust, cut and resolder loads of bent and shorted pins on the soldering side before I dared to insert a CPU and RAM and turn this thing on.
As expected it was still dead. The reason were lots of loosened pins art the 85C206 that needed to be resoldered completely.
Then it came alive again and I began fiddling with the jumpers because I couldn´t find anything on the net about this board that has printed "386IE-B-3-0" in the upper right corner.

Initially I had populated all cache sockets for 256K but no matter what combination of cache and TAG chips I tried cache was either not recognized or the whole system was unstable.
Then I finally found a nearly identical ABIT board, the AB-FS3 (or AB-FS333, AB-FS340):
https://theretroweb.com/motherboards/s/abit-ab-fs3

Even the numbering of the components is identical, mine has 2 additional 72-pin SIMM slots and no jumper-array for cache size just two single jumpers besides the DIL sockets.

In the jumper manual I learned that for 256K cache you have to populate 2 x 64K x 4 TAG chips that are quite uncommon today (and probably back then). So I ordered 2 chips and postponed the cache issue.

According to the manual for the ABIT board the maximum RAM is 32MB. I tried all sorts of combinations but I´m stuck at 16 MB maximum so far.
Does anyone know if the SIS "Rabbit"-chipset can handle 32MB? Or are there additional requirements to be met?