Help to ID 1964-65 Muncie 4 speed

[jeffschevelle]

The 3780 beginning part number does not make sense for a 64 or 65 Muncie trans. 3780 correlates to part numbers originally issued in about 1960 or 1961. Numbers of course can continue to be used for years, but since Muncie's did not first exist until 1963 that would not be the case here. For example, the part number listed in the AIM for a 1964 Chevelle Muncie (wide ratio) is 3841435.

So the tag probably does not go with that trans.

You can at least narrow down the maincase to being original to either a 64 or a 65 trans. 64 maincases have a smaller rounded casting boss on the top rear center of the case (where it is drilled and tapped for the hole for the top center tail housing bolt). 65's have a much larger rectangular boss which looks like 66 and later cases.