Need help identifying a tractor

I'm a realtor and was at a home today that I will be listing and asked the owner if the tractor was going to convey with the house. He said, "Yeah, unless I can find someone who wants to buy it." Being a gearhead in general (with no tactor experience, but I aspire to own one) I've been thinking about that. I would love to own it but probably won't. I figured I'd try to help him out and help out anyone who might want to buy it. He claims it's a "1938 Allis D". The few minutes of google research I've done tell me that it's not that simple. So I figured I'd ask if anyone can tell me what to look for next time I'm there to help identify the old tractor. It has what appears to be a channel type frame (enough different than most tractors that it caught my eye). It's a smaller tractor and has some sort of green (pretty light duty looking) mowing deck suspended from it. (this has nothing to do with the model...but oh well). I'll be there sometime this week with a digital camera and some time. What and where do I need to look to learn about this and establish a rough value?

Thanks!
Alex
Columbia MO

It's an hour away from me so I'll try to get some photos and scrounge around for a serial number when I get up there next. It had a narrow front end, looked pretty sad, flat rear tire(s)...etc. He claimed it took 5 hours of work for every hour of run time so he bought a lawn tractor for his 3 acres ;).
Thanks again,
Alex

Take a couple of photos and post them on this site in the "tractor photos" section. With a channel frame, it could be a WD or WD45 or maybe a WC. Also could be others. Once you post the pictures we'll have a good idea of what it is and then we can tell you where to look for the serial number--that will confirm model and year made.