There are a lot of folks on here that know there Model A Fords and probably a fair amout that have a farming back ground. I imagine the numbers dwindle quite a lot when you are looking for Baldwin/Gleaner combine parts. If you know the model number of the combine from which the part you need comes from then I would suggest checking with the antique tractor/combine parts network. There are quite a few folks dedicated to maintaining and restoring the old farm equipment so there are probably quite a few web-sites for this activity. My dad used the old Baldwin/Gleaner combines when he started farming in 1948 but sold them many years ago and I think they were too new to have the Ford industrial/Model A powerplant. I've seen quite a few tractor/combine salvage yards in my travels and I figure they have a pretty good network for parts searches.
Hope you find the parts you need
Kerby