Rick91gt sells Stainless steel bolt in ones, you could weld them also if you wanted. I have them in my car, nice pieces for a nice price from a great guy. Good luck.
Mike.
Click on the link in my Sig if you'd like to inquire about his torque boxes. He won't quote you a price in teh forums but he'll PM you one if you ask him.
Looks about the same as I got on ebay a long time ago. I think I got mine from dynamic racing products??? Seem fairly decent with some really good welds and they are a very dense metal with all grade 8 hardware meant to be bolted but strongly suggested to be welded also.
You know I see guys having some issues with the uppers and I have never had any issues in a good condition car after fully welding in the upper seams. I'm working on a upper kit like no other currently available, I actually came up with something like the S-box a few years back. Shame on me for not marketing it
Welding the lower re enforcement kit is really is not needed, you can not get any decent penatration in the lower section that goes up inside the stock frame. If I weld anything it is the upper plate (located under the rear seat) to the floor. I still prefer to weld the lower seams as well for extra protection.