Don,

I ran across these in the Wicks booth at OSH..
http://www.wicksaircraft.com/catalog/product_cat.php/subid=3367/index.ht
ml  The 3" Metal Vents #SV-3GR are not the same quality as Wemac but they
look good.  I got lucky in the Fly Market and found a pair of surplus unused 2 3/4"
Wemacs for $90, funkey color but functional.  In this case, size matters
so the 3" would be my next choice, can't get too much air on a hot day
down low.

Steve Colwell