Based on the tongue weight you listed having and needing a larger drop shank the Equal-i-Zer Weight Distribution system you'd want is the part # EQ37141ET which has a tongue weight range of 1,000 lb to 1,400 lbs.
For lifted trucks like yours a larger drop shank like the part # EQ90-02-4400 would be your best option as it allows you to do drops up to 9 inches which is about right for a truck like yours with a 2 inch lift. view full answer...