1999 Chevy 5.7 Distributor Cap problem (broken fixture under cap)

But here's the problem... 1999 Chevy 5.7 is the motor. I was doing a plug/wires/cap/rotor swap because it started running rough and like crap. New plugs, and it was much better. So I did the wires, cap and rotor... BUT... When I was screwing the distributor cap back on (two real small torx-head screws, the housing in whatever the CAP screws onto broke. It was the one in the rear, and the damn thing is PLASTIC!! http://65.42.106.152/forums/images/smilies/motz2.gif So now I can't screw the distributor cap back on. I'm totally lost. I was hoping that maybe someone might know something about this, what that part IS that the distributor cap screws onto, and if it's readily replaceable by ME, or have I gone and really mucked things up? http://65.42.106.152/forums/images/ubb/frown.gif Again, this MIGHT be relevant should someone be doing a 350 swap... because BEWARE.... a small screw housing that broke off can prevent the cap from going on. THANKS, please!