2005 YZ450F and YZ250F will have an aluminum frame. The sales guy down at DelAmo sports assures me this to be true. I told him I thought that was only for the 125 and 250. Being as he was the sales guy and should know more than me just the lowly consumer I did not argue it with him. I am just stoked to get a new 450 with an aluminum frame before anyone else. I'll be sure to post my first report when I take delivery and of course pics will follow.