Help Identifying Transformer Pinout (Hammond 900 Series)

[aprats]

Hello friends, I recently picked up a trio of Hammond 917 Bridging Line to Line transformers. According to the sales sheet, they have a 2500 / 10000 primary and 125 / 200 / 500 secondary. I reached out to Hammond for the pinout and it was a dead end. I'm new to identifying transformers—and diy audio in general. I measured between pins and found the attached.

1. What's your best guess on which pairs line up with the specified impedances?
2. If I wanted to wire these up with rotary switches to switch between the different impedances, what would that look like? DP3T on the secondary and DPDT on the primary?
3. How would I determine what pin the shield is?