[Dave Cleveland]

Okay, this may sound a little strange but it might be worth your while. I used crevis tools from a vacuum cleaner. I know, I know, hardly authentic, but they seem to work well. I simply plugged the ends with a high temp. RTV and cut slots and holes in it as needed. The hose slips on the end and the whole thing fits neatly up under the dash. They only hang down about two inches and the hoses come in from the sides of the body instead of from the bottom.
I know it sounds silly, but it's working for me. Plus, I have more room under my dash.
At best, you've got inexpensive vents, at worst, you're out about 10 bucks.
Just my $.02

DaveC