Found the axle code, it is 19, so non-limited slip, 3.55 gears.
According to this site
2009 towingmax tow is 7800 lbs - now that would be with certain equipment that I haven't confirmed I have yet (namely, the towing package) so I'm going to guesstimate probably 6000 lbs. I checked the hitch and it's aftermarket - Drawtite. It does NOT have the factory 7 pin, so minimal towing of a pontoon is what I plan on, until I can upgrade it.
edit: adding the 535 package, which includes the radiator upgrade, hitch, and controller plus bigger battery - that must be the max of 7800 lbs. So I'll just tow under 5k and should be ok.