should I stick with the GM's or go with after market slotted to help with my braking? If going aftermarket what brand/vendor? We pull a 40' 8 horse trailer so any and all suggestions welcomed!

Read this please http://www.dieselplace.com/forum/showthread.php?t=326496
Especially post #2.

And here http://www.dieselplace.com/forum/showthread.php?t=323072&highlight=rotors

http://www.dieselplace.com/forum/showthread.php?t=274010&highlight=rotors

http://www.dieselplace.com/forum/showpost.php?p=3454266&postcount=5