Darren, your best reference for loggers is these guys: http://www.thetimbershop.proboards.com/index.cgi Everything you wanted to know about loggers, but was affraid to ask; these guys know. William (muleskinner), Mark (loghauler70) Mike (tufftin), Ryan Ronning, & Dave (slurrydog) are a great guys with a ton of knowledge about logging.
Good luck, have fun, pust pics.
Oh, one thing I do know about log trucks is you need to extend the frame behind the rear tandems about 5ft (scale) from the center of he tandems or the log trailer won't work properly. Muleskinner told me that!