Lol....no i am not going to try to weld the two together...because first of all....the subframe is aluminum and the frame is steel....so thats out the window.....the reason i am doing this instead of modifying the stock frame is because its garunteed to fit the seats and plastics right...and it is removable...like specr said its allot easier to replace a subframe than your whole frame. so what i am planning to do is cut off the entire subframe...grind where the subframe was connected to the frame clean...and then weld basically tabs if you will...one on each side of the mount for the f4 or f4i subframe...so then it will fit tightly it will not move side to side. then simply drill holes through and bolt it up to the frame. AHhhh i need someone to help with the frame differences, im lost on that