Can not decide if this a buggy/wagon wrench or a farm implement wrench.  Any ideas?

if the big end ain't offset i consider it implement.

The offset on a wagon/buggy wrench is to get into the hub where the axle nut is, so yes, more or less..

But the light steel wheels, like those on drag behind farm equipment sometimes had flush mounted axle nuts...

Given that several makers of farm implements made buggies and wagons, and sold them to farmers, the distinction may be a bit pointless tho.

The markings on the end with the smaller openings may be a valuable clue to identification.  I can't make them out for sure, and are there any on the other side?

No markings on other side.  It is a four digit # last three are 219, first # not readable but maybe a 8, 9, 3, or 2.

Rathbone lists a C219 as a Kingman Plow co. wrench but no photo or parts list illustration. In Rathbone's Volume Two page 123 there is a photo of the same style wrench as yours but marked "D239" under Kingman Plow Co.

 I have what looks to be same wrench Clearly marked D239. For an unknown reason I had it marked Rock Island but don't find a reason for that attribution.I'll go along with Kingman. Hey Bus don,t confuse us old folks that's in vol 3.

After further reflection it was attributed to Rock Island because Rathbone attributes D239 to Rock Island and Virgil Saak's auction item 825 shows this D239 as Rock Island.

York auction (#675) has a better picture and an updated description/identification.

Leaving only the question, is there also some other Rock Island wrench marked D239? LOL

Mine is D239, now that I had help with the hard to read parts.  Thanks to all!

The two different D239 wrenches from the Virgil Saak Auction Lot 825 are shown below. The bottom one is the
wrench shown in Rock Island Parts Books. The top one is the one shown in Rathbone Volume Three as A Kingman Plow Co. wrench but I have not seen a parts list example yet. Volume Three had not been published when I wrote up the Saak auction.