i am about to start a tri-axle rig myself using a kenworth w900 truck. i found 2 of them on ebay for a decent price so i can have all the extra parts needed to extend and have the correct suspension and matching wheels and tires. i'm also extending the frame to accommodate a 2nd flat top sleeper and leaving the front aerodie one the way it is. i'm also building a scratch built rack that will sit over the flat top sleeper and a deck right on top of the frame because it will be a car carrier with matching trailer when it's complete, oh also it will have a 2nd set of steering wheels and axle between the 1st and 2nd fuel tanks under the sleeper because of how long it will be. i hope to get it started in the next few days when my 2nd truck arrives in the mail.