Slick 60's

Is a three speed in a 65/cyl the same as hung on the back of a Y block?

the tranny was on a 65 f100 6cyl what i need to know is tranny to bellhosing ect. to replace on 292 y block?

early trans 61-64 have a fat spline on the input shaft
65/66 2wd trans have a skinny spline on the input shaft.

length of input shaft may be longer on the early ones too.

Thanks Iceman