As mentioned, the earlier FE bellhousings had a smaller diameter front bearing retainer bore size, as well as only the narrow transmission bolt pattern. I have a 1961 bellhousing behind the 428 CJ in my 59, as well as a Toploader 4 speed.I could have either had the Toploader (1966 model) bearing retainer turned down to the right diameter, or looked for a 1964 only Toploader retainer, but I chose to have the hole in the bellhousing machined to the proper bore size. I used a later 184 tooth flywheel and starter, as well as a 65 & newer steel block plate, to locate the starter, The early bells used the long shaft design starter motors, which did not use a block plate, as the early starters had a machined ridge, which fit into a corresponding recess in the bellhousing itself. It works just fine with a Mcleod 11" Long style clutch.