Nothing less than an acetylene torch is practical to cut through a Toyota FJ frame. The inside wall hole of the boxed front crossmember will have to be at least two inches wider in diameter to accommodate the lower slip joint, as the gear box butts against the frame. In our FJ frame, a rear hole already exists. Before making any tack welds, C-clamp the box and measure the proper shaft lengths, U-joint included. All cuts should be smoothed inside and out, to eliminate the rough edges, then primed to help prevent rust. In addition, this is a good time to check motor-mount and other frame clearances. We had to cut away a piece of crossmember (top) to allow the lower slip joint to fit.