Have welded up the rings around the drain plugs way too many times. Made it a bit stronger with some 1/2" plate!![]()
After grinding off a few diff plug heads I now use the 10mm hex key plug.
Worst case they fill with mud, but do not deform. I get them at the Toy dealer. Look like 3022m below.
http://www.cgenterprises.com/diff_plugs.htm