The stock manifolds are notorius for cracking on the passenger side, as you have already discovered. JB wel won't be strong enough, and I'd be worried about the heat that it will be exposed to. If you can get the manifold up and to me (I'll be in Staford this weekend working on my ranger mud truck), I can try to weld it up for ya. But the best bet is to get a set of the Motorsport shorty headers for your truck. The pair costs a little less than 1 of the stock manifolds, plus you won't need to mess with the rest of the exhaust system until you are ready. In other words they bolt in with no additional mods, unlike some of the other off-the-shelf shortys. Now if you can't afford to do that, run to the local junk yard and find you a decent shape passenger manifold and pull that. The Widewater pick-and-pull in Stafford has a few mid-late 90's trucks that you can pull the manifold off of, and that place it pretty cheap, you just need to bring your own tools.