Both Ford and Chevy had the higher HP engines and better transmissions beginning in 2006. For the model years you are looking at I would prefer the Chevy because of the Allison transmission. Also prefer the full basement storage over small cutout type doors on the newer Thor MH’s. The older models usually come with more FW capacity and are farther down the depreciation curve. Your decision will be based on how you plan to use the MH. If you have kids some of the newer Thor MH’s have more sleeping positions. The chassis will be Ford and will have another gear in the transmission and 320 HP vs 362 HP of the 2006 &07 models.