My father got this cat from his father who owned a small sawmill.  Dad says that it was the first ones made.  It has had changes made as it was a working cat.  Wider tracks and has newer rails.  Last ran in 2009.  

New photos showing 1925 date.
Wide tracks, straight front blade.
Dad says the starting engine is gas and is in great shape!
 

in addition to this post of the RD4 antique cat: I do have more photos and information available.

Welcome to the group, we always like pictures. Probably as many if not more old Cats working than all painted up for show tractors.

Welcome! Heck, don't keep us in suspense, tell us some more about the RD4 please. If you don't, I'll have to bore some folks here with one of my own stories, and they wouldn't like that much! JM

Thanks. I do have a few more photos.

My grandfather used it for his sawmill which was used to cut timber.  He made some changes because it was necessary for the job it was doing.  He replaced the narrow tracks with wider ones.  It has a straight blade on it.  He had just replaced the rails a short time before he passed away.  He had told my dad that that cat model was from the first of that model.  That he had bought it the year it came out.

Dad moved it from the mill to his property in 2009.  He drove it onto a trailer and drove it off again.  It has not been started since then, but it was working.  Dad said that it has a good gas starting motor on it.
 

Taynton wrote:

Thanks. I do have a few more photos.