AEV's Colorado Rear Differential Cover is designed specifically for the Dana M220 axle found in most 2015 & newer Chevy Colorado/GMC Canyon trucks - including ZR2 and ZR2 Bison . This heavy duty, nodular iron Differential Cover features a fluid level port, placed at the correct level to meet factory specifications, eliminating the need to guess on oil level or use a dipstick to figure out the correct amount of oil. For added convenience, all AEV Differential Covers feature an oversized oil fill port located on the top of the cover. This fill port not only allows you to easily add fluid in the field if axle repairs are necessary, but also doubles as an inspection port, allowing the user to see inside the differential, inspect ring gear teeth, look for water intrusion or even use a dial indicator to inspect for problems without ever removing the cover.