Don't waste your $$ on the Judy
Don't waste your $$ on the Rock Shok Judy-they are OK, but not much better than what you have,and a used Judy isn't worth much more than $35-$40.You can get a decent used SID for under $150.Same story for a better Manitou or Marzocchi.Don't spend $100 on used(or new) low end stuff when you can get used good stuff for maybe $100-$150.
Try this while looking
1)Does your fork have actual springs??-not those rubber/plastic elastomers like you will find in low end forks?If it is a real spring you can increase the preload with some washers.Go to the hardware store and get about 1" worth -total)of washers that will fit in your fork tube.Put an equal number(maybe just 1/4" worth at 1st) on both sides, and screw the cap back on.Now, screwing the cap might be a two man job now, but you get the idea.Be careful,don't cross thread it-you might have to use a lot of force,so it is easier to not get the threads right.This wil stiffen up the fork a bit.Not stiff enough-add more washers.
2)You could try to buy some higher spring rate springs-for a different fork-on ebay.However, they might not fit in your fork.
3)Does this fork have oil-probably not-if it did you could use thicker oil.
Don't waste any $ other than the $$ for washers on this fork. For $100-$150 get one a 80mm one should be ok(does the XC60 MEAN 60 MM OF TRAVEL??).Get a good enough fk so you can put it on a new bike/frame if you upgrade, or so you can sell it.
Make sure the washers will fit-measure the opening carefully.