My suggestion would be to purchase a stacked plate, low pressure drop (LPD) style cooler, sold either by "Tru-Cool" or "B&M Super Cooler." Both are the same, made by "LONG" and are the best in the industry. Fit the largest cooler you have room for if you tow, crawl, 4x4, etc. or otherwise operate in high heat. Just be advised, you can't mount them with the fittings facing downward.
Ebay is an excellent source, as is
www.bowtieoverdrives.com
Here's the Tru-Cool that I run. Appoximately 11"x11"x1.5"
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Here it is with the 3/4 ton GM fan fitted....
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And the final configuration with the fittings facing correctly (upward in this case) and a bit of stainless shrouding around the original GM fan cage to promote airflow....
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