I had the same problem... when I upgraded to a 3/4 ton a number of years ago I had to get an 8" drop shank. This winter I upgraded TV'S to the dually which has the 2 1/2" hitch... I really don't like the adapter sleeve, it's too sloppy. If I weren't picking up my new 5er today, I would get a new shank in 2.5".
2014 RAM 3500 4x4 CCLB Dually, Cummins / 68RFE / 3.42 / B&W Patriot 16K
2016 Coachmen Chapparral 360IBL
SOLD - 2012 Salem Cruise Lite 281BHXL
SOLD - 2005 Dodge Ram 2500 4x4 QCLB Cummins