'76 318 smoke...

I have not worked on Mopar Small Block's or 904 Torque Flights since the seventies but if you check to see if there is a hard vaccuum line with a short piece of rubber hose on both ends, it would be at the back of the carburetor or the back half of the intake down to the transmission. If that hose has trans fluid being pulled through it you will see it the minute you pull one end of those loose.
That said I'm not entirely sure that your trans has a vaccuum modulator.