Both wrenches were made for Caterpillar by Billings and are stamped 5B783. The bottom wrench in the photos matches the other wrenches in my collection. The bottom wrench has the Billings logo stamped in the 11/16” end and 5B783 stamped in the ¾” end and facing opposite the logo. The top wrench has the Billings logo stamped in the ¾” end and 5B783 stamped in the 11/16” end and facing the same as the logo. The reverse side of the bottom wrench has the size markings facing opposite each other and the top wrench has the numbers facing the same way. The top wrench is also slightly longer and considerably thinner than the bottom wrench. I suspect the thinner wrench is the earlier version. I appreciate any information available.

Interesting observation, I just checked 4 of my 5B783's and they all have the same characteristics as the bottom wrench in your pictures, the one you stated as matching the others you have. I checked all the Caterpillar/Billings wrench sets I have and didn't find any wrenches of any size that differed in dimension from the others carrying the same part numbers. That's an interesting mystery.

Just for kicks I measured the 5B783's I have here, and tip to tip they all are 7 3/4" in length - I would assume that the "normal" wrench you pictured is likely the same.

Thanks for the reply Sasquatch, the “mystery” 5B783 wrench measures 8¼” tip to tip and the wrench heads measure ¼” thick. The “normal” 5B783 wrench is 7¾” tip to tip as you stated and the wrench heads are 3/8” thick.