I find no indication of 35th Infantry Division or any of its elements - 134th, 137th, 138th, 140th & 320th Infantry (formerly an element of 80th Division) - having served in the Canal Zone at any time during the war.
There's a website at < http://www.grunts.net/army/35thid.htmlhttp://www.grunts.net/army/35thid.html > with links to three others (you can go there by clicking on the address in the line above). The division represented the Kansas and Missouri National Guard and reverted to state control at the end of the war. In the late 1960's, the division was reorganized and redesignated 35th Engineer Brigade, Missouri National Gaurd and has been so indentified since. This may account for your difficulty in locating information.
Some time ago I researched a couple brothers named Keen. One, 24 year-old Corporal Lenzy L. Keen, was a member of 73d Coast Artillery (Antiaircraft) at Fort Clayton, Canal Zone. He was shot during a barracks altercation in February 1942, died at Gorgas Hospital and was interred at Corozal Cemetery, Corozal. This has nothing to do with your inquiry except that your mention of the 73d prompted this recollection. (The other, Corporal John R. Keen, was killed in action while serving with the 18th Infantry in Tunisia in July 1943. Their mother, Jennie, was devastated and never fully recovered from the shock. They were her only sons.)
Your subject probably served with the 73d in Panama prior to joining the 35th later - almost certainly as a replacement - somewhere between the U. S. and France. No way to tell without more information.
You might want to order his deceased file. You'll find practical instructions at Message #2112. Go back to the main page, enter "2112" in the box in the upper right corner marked, "Jump to #_____" then click on "Go".