The c4 24 spline went to 1969 the 26 spline was from 1971 on up. The 70 was an odd ball with either spline. also the 1970 on up was a stronger trans with larger clutch packs
1964 were 5 bolt bells and 1965 on up were 6 bolt bells, You can bolt a V8 bell on a 6 cylinder c4
The case fill and...