The gasket on the side of the engine will be one for the water between the two heads most of our Massey's with the sisu engine have had them. Massey's are a 20min job to fix but I've heard the fastracs have a lot of stuff in the way and take a lot longerJust thought I would update. Spoke to local AD guys who run 4 4220 s which are literally a year old next week. All have clocked 1950 hrs plus.
All 4 have had a gasket on side of engine fail, 3 have had rear diffs fail and 3 have had hubs fail . They love the comfort and speed/ safety but find them underpowered loaded.
Description was, they are ok, sort of !!
Be intresting how they cope with a second busy year.