Photo taken by James McCray in April 2017
BH Photo #456143
Looking at a satellite view of the Jake's Garage area, you can see there used to be two bridges. One was east of Jake's Garage, over the Deep Fork. This is the site of the abutment with the Jake's Garage sign painted on it in the Flickr photo. The other bridge was northeast of Jake's, to cross the railroad tracks (which are gone).
I agree with you this probably was part of the bridge over the Deep Fork, though maybe not the main span. I was unable to find information on the date that alignment of Rt 66 was abandoned.
I believe that this bridge has been relocated. I think this bridge is the original Route 66 bridge (http://bridgehunter.com/ok/oklahoma/bh42978/) and was just moved to make the driveway entrance for Jake's Garage. If one looks at the Flicker link for http://bridgehunter.com/ok/oklahoma/bh42978/ one can see that the bridge has been listed as "lost" on this site but a flicker link pic shows that the abutments remain with the advertizement for Jake's Garage. Anyway, any help will be welcome to confirm my theory.