Ford made a fairly limited number of small-block case C-6's, if you have one, it's VERY rare.
not without an adapter.
Edit: Unless you bought a C6 for a small block, which at 1970 do not think was available.
If it has the same configuration of your old c4 it will. If it bolts up to the engine it will work.
It's a little late to be asking wouldn't you say.
Ok I have a 1976 f100 with a 302 small block that currently has a c4 transmission that went out. I went and bought a 1970 c6 transmission. Will the c6 work on my truck it's for a small block