With all the different 2-letter designations being tossed about for the various Jeeps it can be a little confusing when looking for parts.  Here's a quick breakdown for you:

• CJ - Built from 1944 to 1986 there were several models of the CJ Jeep.
• 1944-1945 CJ-2
• 1945-1949 CJ-2A
• 1949-1953 CJ-3A
• 1953-1968 CJ-3B
• 1955-1983 CJ-5
• 1956-1975 CJ-6
• 1976-1986 CJ-7
• 1981-1986 CJ-8 (Scrambler)

• YJ Wrangler - Built 1987-1995

• TJ Wrangler - Built 1997-2006
• Unlimited models were referred to as LJ Wranglers.  Most of the parts are interchangeable between the LJ and TJ except for anything related to the longer body (rear corner panels, cargo carpet, etc).
• 1997 models are different from 1998-2006 for some accessories.

• SJ (or FSJ) - Fullsize Cherokee/Wagoneer built between 1962-1991.  These were the big, boxy Cherokee/Wagoneer bodies with a real frame.

• XJ Cherokee/Wagoneer - Built between 1984-2001.  These were the mid-size Cherokee/Wagoneer bodies using a uniframe design (frame incorporated into the body).

• WJ Grand Cherokee - Built between 1999-2004

• ZJ Grand Cherokeee - Built between 1993-1998

• WK Grand Cherokee - Built between 2005-2006

• KJ Liberty - Built between 2002-2007 (replaced the XJ Cherokee)

• JK Wrangler - Built between 2007-2008 (replaced the TJ/LJ Wrangler)

This is a basic outline for what model Jeep you have when people start throwing around the 2-letter names.