Quote Originally Posted by Stovebolter
....I have a total workable space of 18x25 and approximately 3 1/2" of depth....
Spal makes a low profile 16" fan with a depth of 2.05" but it is only rated for about 1300 CFM. Part # VA18-AP10/C-41A $ 79.95

Zirgo has several 16" fans available rated between 2800-3000 CFM fan but they're all 3.5" deep - maybe too deep for your application.

I installed a 16" Sidewinder fan from The Fan Man on a '64 Ranchero that worked great, but costs $ 420.00. The fan is driven by an enclosed belt from an offset motor. The depth at the center is 1 7/8" and 3 3/8" on the side where the motor is, and they claim it moves over 2200 CFM. (I see on their web site that it is currently unavailable due to redesign). I installed it three years ago, and haven't had any complaints on it from the customer.

Hope this helps.

Joe