joey,
This subject comes up a ton, and I know we all have given out numerous suggestions on who might be able to give you that info. Unfortunately, all the guys who have asked never came back with the answer, and that is a shame.
All I can suggest is asking companies who use them and hopefully you get lucky with someone willing to divulge the answer. Please stop back and let us know if you do find that company.
Here are some to try
Double Eagle sleepers -->
http://www.doubleeagleind.com
ICT -->
http://www.trucksleeper.com/
AA Sleepers -->
http://www.aatrucksleeper.com/index.html