"KL? MJ? XJ? ZJ? WK???"
 

Where exactly do these letters come from? How am I supposed to know if I have a "KL" other than seeing everybody with a 2019 calling it a "KL" is this an official jeep lettering system?

Thanks, much appreciated

Funny, Quadratec omitted KL from their list.

KL = 2014+ Cherokee
MJ = 1986-1992 Comanche
XJ = 1984-2001 Cherokee
ZJ = 1993-1998 Grand Cherokee
WJ = 1999-2004 Grand Cherokee
WK = 2005-2010 Grand Cherokee
WK2 = 2011-2020 Grand Cherokee

They're all just internal "letter codes"... pretty all manufacturers use either a two-letter or three-letter system to identify all of their vehicles internally.