Hello Tyler A warm welcome from me to these forums.
A number of small engineering companies made edgers ... mainly because they were of simple design.
I think this a typical example of one of those ventures. I do not know who Withco was.
This edger is powered by a 1970s Victa Industrial Unit. From the earliest of days, Victa's intention was to sell its engines to other OEMs (original equipment manufacturers).
Many thanks for the great images of the Withco Edger. I hope more information comes to light about the maker.
Hope this helps. ----------------------------- Jack