I bought that gearbox about 18 months ago for another project, but didn't end up using it......but I have now.
It is a 30:1 reduction, Worn and Wheel gearbox.
I bought it brand new off ebay.
The motorbike sprokets give me a further reduction of 2.75:1.
I made some stabilizing feet so they can take the weight off the wheels a bit when getting stuck into the body work.
The thread isn't revealed when raising or lowering the feet.