Check out this company from Wisconsin, Classic Enterprises at http://classicent.com/jeep.php
. They make full OE replacements for the torque box (the metal box that mates the body mounts to the tub). I ordered both sides for my 99 TJ and was 100% impressed with the quality and attention to detail. Their metal work is heavy duty and each torque box is hand signed by the fabricator with their name and 'Made in the USA' which shows they are taking pride in their product. Order these and it will solve your problem for the rest of your jeep's life.
Once you get them, it's just a matter of removing your mounts, grinding out the old box and welding in the new one. Be sure to hit the bolts on the mounts with some PB or similar because if they're like mine they will be fused on there.
Don't wait too long on this either. Now that the metal is rusted and compromised, salt etc from the roads will be blasting in there and you don't want that rust migrating from the torque box into the tub which will just compound the problem.
One final suggestion: before ordering, check the other side of your jeep too. My drivers side was like yours and thought my passenger side looked ok at a glance. On closer inspection, it was starting to flake just a tiny bit and with a little picking, I discovered it was basically held together by some paint and needed replacing too. I saved some money on shipping by ordering both sides at the same time.