hmm... I am going to use some red rubber gasket material when I make my splash guard cuz mine are all cracked and broken. I get for free from my dads work, but its usually really expensive. It is used to make gaskets for pipes in refineries and stuff like that.
Do you have the metal "skidplate" that mounts at the front crossmember? I bet if you don't have that either it would be hard to keep an alternator alive.