Not too sure on the mm-inch conversion and dont really feel like searching for it at the moment but the premium shock length for a clodbuster is 3.75-4.25in

It gives you plenty of extra shock for droop and lots of oil to keep the truck super plush. You'll find that depending on the geometry and shock length you can run softer setups with longer shocks which allows you to set the ride height lower and get a really forgiving truck that will be alot more stable.

A shorter shock like say 3.5in will work okay but you really have to get the geometry and setup correct or it will be hard to get the truck to handle.

just my 2c