Just measured mine, the slide sticks out 23 1/4" on the top, 24 1/2" on the bottom. Never noticed this before, but might be because the slide needs to tip slightly and move up as it retracts, therefore making it parellel with the TT side when closed. If you watch while the slide opens, it actually moves out and down. This makes it more flush with the TT floor.
2015 Starcraft Travel Star 299BHU Black Pearl Edition
2011 Jayco X23J (traded in)
2009 Ford F150 FX4 SuperCrew