It looks like it was built on a fairly stout truck chassis, does it have dual rear wheels?
Around that time, GMC would have been building a large inline 6 for something like this, so perhaps 60 - 80 horsepower?
They where limited to only about 100 HP with the 6.5:1 compression ratio and 80 or so octane gas around the 20's.
When moonshiners put the Ford V8's into a car, they usually raised the compression to 8:1 and started adding
moonshine to keep it from pinging on the low quality gas availible in the 30's.