New AA trucks, need help with ID

[D2G2]

Hi I am new to Model AA trucks (and model A cars also), I've found what I think are two AA's but I am confused by their different hubs, read end, and what I think might be an overdrive. Both trucks are in rough condition, missing parts, but reading posts and looking at pictures on this forum makes me think I might take a shot at these guys. Pictures 1 and 2 are of the truck with thin or light hubs (front & back) and some kind of gear box behind the transmission, pictures #3 is of a truck with heavy hubs (front & back) and a read end that looks different from worm drive on the first truck. I didn't have much time to shoot pictures, we were loading some heavy equipment, but I may be going back there next weekend and could shoot more pictures. Please take a look the pictures and let me know what you think.
Thanks, Glenn (aka D2G2)

[REM]

First welcome to the site and the AA hobby.
These old trucks are fun.

Pictures 1 & 2 are of a 1928 or 29 which would be correct with the worm drive rear, smaller hubs and single rear wheels. The other pic would be of a 1930 or 31 which were built with the heavier bevel gear rear, bigger hubs and probably dual rear wheels.
The 30/31 should have a 4 speed trans. and the other probably a 3 speed with the auxillary trans (probably an underdrive) shown in the pictures.
Richard

[Watermelon Truck]

The truck with the worm drive looks to be a 1928 due to the red steering wheel and also the E brake lever looks to be on left side of cab.It also has the hubs and drums for the early spoke AA wheel.

[D2G2]

Thanks for the info guys,
Ok, now for the "how high is up" questions:

* how much interchange is there on the body parts, for instance; could you put the 30/31 cab and right fender on the 28 frame and bed and use the doors from the 28?

* how much interchange is there with the running gear; like the 28 engine, 30/31 transmission, 28 overdrive and 30/31 rear end?

* what was the gear ratio of the 30/31 rear?

Between them, there may be enough tin and running gear to get 1/2 way towards a running truck.

Thanks again, this is a great forum, Glenn

[Watermelon Truck]

do the trucks both have a cab and if so are the cabs the same or is one a more rounded design .Depending on your plan.I would get both trucks and then figure out do I want a 1928 with spoke wheels or a 1930 style with bud wheels 4 sp and bevel gear axle ,For a driver the bevel gear would be a better choice.