Your sled is a real trail carver,low slung,and they handle great when set up right.Those engines are sweet too,and while maybe not the most powerful they give excellent fuel mileage.5500 miles isn't too high but if you have access to a compression tester it might be worth a check to see how the rings are seating.If you can find one the suspension manual put out by Yamaha is worth owning too,it'll show you how to service the skid and set it up to your weight.Getting the shocks rebuilt and revalved would certainly be worth doing too,I found my SRX was valved overly stiff and rode like a truck.Betheviper has a nice article on the Yamaha skid too and it is well worth the read,just search his name and you'll find it.
There's a few spots on the rear skid that don't have grease fittings but can be added and one is the front W arm mounts.There's 2 L shaped brackets that are bolted to the rails and the W arm bolts to them.Those mounts have bushings and collars in them and I'd be willing to bet they are toast,especially if they've never been taken apart and greased.If your handy with a drill and a tap you can put a grease fitting into the L brackets to help get grease into this area because it is a pain to service.Also if you have the W arm off check it over well because they are known to crack in a few spots,just weld the cracks up and add some gussets in a couple of spots and you should be good.
