I don't think that is a dropped axle, it looks more like a pickup axle (Ford or Chevy) with the mounting pads ground off.
That trans is either a th350 or 400, hard to tell from the pictures. What is the pan shape........350 has a diagonal section to the pan and a 400 is an odd shape.
I'd say it's a Chev pu axle with the leaf spring mounts trimmed off - to find if it is, look on the part of the center web where it starts to curve up you should find raised letters, GM and a part number.