I have what would be termed a "franken-treadle". It has a top from a Singer coffin top and the irons are Elgin, the drawers had to come off so that the top would fit the wider irons. It all works very well together and is very easy to treadle.
If I recall correctly Elgin was made by The Free sewing machine company and has ball bearings in the treadle somewhere.
Sharon in Texas