right thats definatley a dana axle case to get somwhere close to sensible gearing you,ll need to swap the innards for somthing like the dana 44 fitted to the two wheel drive jeep j20 wagoneer! if you open up the back cover and count the teeth on the crown wheel i might be able to help out abit more!
I went to the Dana site and I couldn't find an exact match to this axle. Also the Dana site sez all Dana axles have an ID and model number in the web casting at the back of the pumpkin housing.
I'd LIKE it to be a Dana, but I need to know what model axle it is to get the gears. This axle is also a little weird in that it appears to be upside down but I THINK I have it oriented as the manufacturer intended- there looks to be a vent on top and a drain plug on the bottom as it sits now in my trike. I am told that the gears were probably designed to carry oil up and over...
Overall width is 40" . I don't recall the tooth count but probably wrote it down somewhere when we had the thing apart at the machine shop...
you can see more pix of the build in progress here:
http://adventuresidecar.com/Piglet/piglet.htm