I just finished installing a 6.0 cooler on my 7.3 Superduty, this a bolt on replacement with the exception of splicing tranny lines for the bigger 1/2 lines the new cooler uses.
This cooler will make your trans run any were from 30-60 degrees cooler and you're pretty much can't over heat your trans, great for us plow guys.
My detailed write up of how to do it can be seen here:
http://powerstrokenation.com/forums/showthread.php?t=15508
The stock 6.0 Powerstroke transmission cooler does an ample job of keeping temperatures down, but as the loads increase, so do transmission temps. The 37-row Mishimoto stacked plate cooler provides a larger surface area over both of the stock coolers. Core volume is increased by a whopping 21%, and fluid capacity is increased by 1/3 qt. Shop AutoZone for Ford F250 Super Duty Transmission Cooler Line Assembly. Buy online and pick up in store, or get fast, free delivery on qualified orders. 1-22 of 22 Results. 1-22 of 22 Results. Dorman (20) Duralast (2) PRICE. $15 - $20 (1) $20 - $25 (1) $25 - $30 (2).
6.0 Transmission Cooler For 7.3
Put Transmission oil cooler in 2010 Sierra 1500 to tow dump trailer. Install was a snap since heavy 1/2 ton had small one in place. About 3 times the surface area of OEM cooler and dropped operating transmission temp 20% ( or about 35 degrees under load). Happy with purchase.