Had a driveshaft split on me. Gears tore a hole in the chain case housing so all that chain case had to be repaired in addition to drive shaft adn bearings. My repairs are going well until I realized that the new chain case housing doesn't have the threaded inserts. I bought some L-nut inserts but was wondering how those are installed. Do I have to have those pressed in somehow? If so, what are the specs?