GeneD14, no my 310 doesn't have a ROPS. I have seen some John Deeres that had 3" round tube ROPs though. I think that 1/4"--3/8" wall would work well for your machine.
If you don't mind me asking, what did you have to pay for
your 310? I am envious of a 500hr machine that old. /forums/images/graemlins/ooo.gif Mine has over 10,500 hrs. /forums/images/graemlins/blush.gif I am currently in the process of a partial refurbishment. Valve job, new radiator, new hydraulic pump, new lift & angle hydraulics,some new bushings, all new hoses. I'm having a hard time finding a good place to install a hydraulic filter. Oh, and paint and all new decals. /forums/images/graemlins/smile.gif Good luck with your new loader.
Brian