If you do a search on the forum, this has been discussed in numerous threads. Bottom line is, with a slider hitch, any of the short beds can be made to work. If you have a 3/4 truck (2500/F-250), you'll get the 6.5' bed (approx) which is good for almost all new 5ers without the slider...but it is still recommended for "peace of mind".
Ed and Sharon
2010 Wildcat 28RKBS
2011 Ford F-250 XLT, 6.7L PSD
Ride-Rite Airbags and Airlift wireless remote compressor...nice!
I thought I was wrong once, but I was wrong!