Now for that ProtoType I mentioned earlier, for years now this tractor has intrigued me as I could not figure out what type of engine was in it. After blowing up the pictures and studying them more closely I really believe this is a 6 cylinder Hercules engine in this tractor. This would make sence as if they tried the six cylinder first and it was too heavy so they went with the four cylinder. The hand crank out the front looks like some I have seen on early Hercules power engines.
I believe this is one of the very first prototypes of the GP it has adjustable front and rear axels just loosen the bolts and slide them where you want them. Also the Steering tierod pipe has adjuster locks with sliders, Just loosen the lock nut and slide it where you want it. It has the Wallis type aircleaner on it also the 4 bar steering wheel. The steering colum has a lower hole position for when using it from an Impliment behind. I have never seen wheels like these ever....
If you look close at the picture from the l right rear it appears to have 6 spark plugs sticking up also the hood is much longer than any others. The distributer cap is sticking up by the water pump on the left side of the engine just like a JXD Hercules would. There is a rod going from left side of the battery box that looks like it is for turning the timing or possibly it is a pipe with a wire running through it to power the points in the distributor from the battery.
Malcolm, you need to take a magnifine glass and look closely at the right side of the engine on your brochre or possibly get a good close up scan or good photo to see if this is a 6 cylinder Hercules engine as the picture you posted was of the same tractor as this one.
The rear end it self looks like it is out of a Harry Ferguson. And the picture just wouldn't be right without a Massey Harris Watch Fob hanging out of your pocket now would it.....These are just a few of the things I noticed, so look closely at the pictures and let me know what I missed