G56 Transmission Bearing and Seal Rebuild Kit BK474

This is the full bearing and seal overhaul kit for the Mercedes-built G56 six-speed manual used behind the 5.9L and 6.7L Cummins in 2005-2018 Ram 2500 and 3500 trucks. It replaces BK474 and covers the tapered roller bearings, races, needle bearings, input and output shaft seals, shift shaft seal, and case gaskets - the wear parts that have to come out and go back in any time the case is split.

The G56 tells you it needs this kit before it fails outright. A whine that changes with road speed but not with clutch position is usually the countershaft or mainshaft bearings. A puddle of fluid on the bellhousing side is the input shaft seal; a wet spot at the tailhousing is the output seal. Once metal starts coming off a spalled race it circulates through the gear train and takes synchros and gear teeth with it, so a bearing job done early is far cheaper than the gearset job it turns into.

On the bench: pull the shift tower and tailhousing, split the case, press the old races out of the case bores and the bearings off the mainshaft and countershaft, then set the new bearings with a driver on the race, never through the rollers. Check your endplay with the shim pack before you seal the case halves, and set the seals square with a proper seal driver so the lip is not cocked. Use the correct manual transmission fluid on refill; the G56 is sensitive to what goes in it.

Note: this kit is bearings, races and seals. Synchronizer rings are not included, so if the truck grinds going into a gear order synchros separately.