I used an 2003 GMC w4500HD (same as isuzu) and have it set up to pull a 36' 5th wheel camper that is around 10K pounds. look for ones with 19.5 wheels. They are the HD models and the GVW is 15.5K with a CGVW of just over 20K. I used a gas model and it does good but is not a speed demon when towing. The width of the axles is good for thes old trucks and the frame is the standard 34" They also have the 6 on 8.75 bolt pattern so 22.5 wheels are available if you want them. Here is a link to my photo bucket album.
http://s1356.beta.photobucket.com/u...amp;_suid=135289750051906278881402328205
