transmission problem vaccuum ?

the trans vacumn mod is contolled by the large vacumn fitting on the intake behind the carb. if you have ac there is usually two connections [ 1 for trans mod 2 nd for ac [if so equipped] you need at least 8-10 in of vacumn at this connection. check all connections for tight fit.check your power brake hose and diaprham as this requires lots of vacumn to operate. collapsed hose as well [could be a cracked or worn diaphram ] perhaps consider a faulty vac mod [ check for trans fluid leaking or damp ness inside of line at the mod.

This may Pic help.

Line to Vac modulator should be metal w/short rubber hose for connection to fittings at each end. Metal line will have an upward bend _/\___ then down to prevent fuel from entering the modulator.