Hello Fast58, I've just read through your thread and elgemcdlf has really given you a lot of good info, but I thought I'd throw my 2 cents worth in. I've just done a CV swap on my '57 F100 panel. The frame on our early trucks is different than the twin I beam trucks in that the bottom of the rail where the CV mounts isn't flat. I leveled the top then cut across the bottom of the frame and along the bottom bend so I could move it up to be level. (I'm not good at explaining this) I then rewelded it and reinforced it with a bottom section off another frame rail. I'm also running a 351 W in mine and had to use the rear sump pan from a newer truck, but also had to dimple the firewall for the driver's side head to clear. I installed my front end with the centerline of the spindles the same as the original straight axle. If I was to do it over, I would move the CV forward 1" as it would really help with pan and firewall clearance. It really is an easy swap as far as front suspension swaps are concerned. Good Luck!!!