Hey,Lastchance! I JUST installed my Fentons and dual stacks on my '55 2nd Series 6500. You'll also NEED the heat kit,to replace the heat-riser in the stock manifold. I have a 261,too. I'm using my stock intake,and single Carter. The truck RUNS GREAT! Better performance and a little better gas mileage! Oh,and the BEST part,is the way she sounds! I am VERY PLEASED with my set-up. I'm not planning on up-grading to dual carbs on my truck. Hope this helps.
