I threw out all my broke bulks but my rear bulks would always break just in front of the upper front hinge pin, Usually just one side would break and it was almost always because of a bad landing from a jump.I don't recall ever breaking a front bulkhead. That said, since I started using an rcsolutions rollcage ,a year or so now, I have not had any broken bulks at all. It really stiffens the chassis between the bumpers to the point that it takes a really insane crash or jump to flex that area where the bulkheads typically break.
I've used jbweld and and other stuff like it and I really think you would be wasting your time with it. Take some jbweld and put a line of it on tinfoil fairly thick and when it dries try to snap it in two, it's really not that hard to do.... much easier than snapping your bulkheads would be so I think the benefit is very minimal if at all.
A lot of people swear by the brace going from the body towers to the shock mount so I made me some of those front and rear to go along with the rollcage just for the heck of it. I can see where they help some but the rollcage still stiffens up the chassis much more by itself.
I just finished upgrading mine to the lst diffs too along with the xxl cvd's and kershaw center dogbones so I think the driveline should be pretty much indestructible now. I think it's a great upgrade.
Here's a few pics
the rear brace I made.

the front brace.
the rc solutions roll cage and a pic of the rear mount for it, the front is the same and it also connects in front of the tranny through the chassis.
