where to buy them.....(the bolt in kind). I found i just cracked one of them, welded them back together last weekend, just making sure the same thing never happens again!
I bought upper and lowers for $70 on ebay. Bolted them in then welded them solid. The boxes had already been welded. I dont haft to worry about them ever again.
UPR has a nice upper/lower set, but it's kinda expensive for what it is. eBay has a lot of different places offering cheaper and similar reinforcement kits. Some are bolt-in/weld-in, some are strictly weld-in deals.
I got a set of uppers and lowers off ebay awhile back. Still haven't gotten around to putting them in but they are bolt in and then if you want to you can weld them in as well. I think they were around $70 like ttop said.