Will this stump grinder work for me?

I'm looking at a bobcat stump grinder SG50 that the seller assured me is standard flow. I'm going to be putting this on a CAT 216 with about 15 gpm of flow per the manual. When I looked at the implement there was a third hydrualic connection on the skid steer and seller said was a pressure relief hose and wasn't needed since my machine didn't have the return connection. I've done some research and it seems like the return is pretty important. Also it seems that the grinder is probably high flow since it has the return line. Seller says his bobcat only has 16gpm and I saw it work and seemed to grind fine. So long an short will this work on my machine? Thanks for the help

I'm pretty familiar with cat machines and some bobcats as far as the newer machines and hi flow goes. The third line is a MUST. Its a case drain, its to bleed off fluid that leaks internally in the hydraulic motor on the grinder...they are found on a lot of hydraulic motor powered attachments. The case drain basically dumps that fluid into the hydraulic oil tank. The 216 we used to have at work had standard flow hydraulics and no case drain. Ask your cat dealer about adding the case drain to your machine, if they can do it, it could be a added fitting or a coupling manifold. I would figure this out before buying it, as you'd probably ruin the stump grinder going by what its current owner says.