I just put a 3.23 in my '49 Coupe for better cruising economy. The 3.63 that came out had been completely gone through during my restoration 5 years (14,000 miles) ago. The shop manual says that some minor grinding on the housing is required to use a 6 cyl. center in a V-8 housing. I guess they beefed up the housing to handle all 135 HP the 303 produced. Anyway, it is available for $150 plus freight.