A couple years ago, just before sears stopped selling catalog, I bought one 
of their plastic marine battery cases, since I had very little rust in this 
area and was paranoid of the possibility.  I was also (and remain) suspect 
of almost any battery I buy, since I had a bad experience with a name brand 
battery going on the leak within a year after I installed it in a previous 
car.  These type battery cases are readily available, and relatively cheap.  
It has worked very well for me.  BTW - you might have to cut an inch or two 
down the side for the cables to come out, and you don't need the case top.

Dean Aukes
'73 Campmobile