Used 3/8 tube, and added a trans cooler thermostat. Not running the 42RH into the stock radiator since those fittings are 5/16" and the O/D unit requires lots of fluid. Used some nice pre bent 3/8" hard lines I got from a 1999 B350 church bus in the junky. Direct bolt in, right down to the line mounting clips. Flared and added -6 AN female fittings to the front of the hard lines, and flex lines. Cooler thermostat bracket is homemade. Everything in mockup stage in pix. Finished up the welding work, sand blasted and primed engine compartment yesterday