There is a difference in width of vertical channels rows in the tank. I believe original had 1/2 inch. Some shops will put in 1/4 inch. I have had both and 1/2 inch works much better. A/C cars also had three rows in lieu of two on non-A/C cars. Check fan clutch operation if not a four blade fan. If a new clutch is needed one that fits in the space is from NAPA (#261306). This was the shortest fan clutch I could find. Clearance between clutch and radiator is 1/4" Rich 64 Belve MW 4spd -- [Non-text portions of this message have been removed] ---- Please address private mail -- mail of interest to only one person -- directly to that person. I.e., send parts/car transactions and negotiations as well as other personal messages only to the intended recipient, not to the Clubhouse public address. This practice will protect your privacy, reduce the total volume of mail and fine tune the content signal to Mopar topic. Thanks! '62 to '65 Mopar Clubhouse Discussion Guidelines: http://www.1962to1965mopar.ornocar.org/mletiq.html.