[Alfisto Steve]

Vac hose feeds vac tank in left wheel well for cruise control and emissions.

As for 3/4 hose for your repair it has to be super thin walled hose not regular bulk heater hose.

 

[Alfisto Steve]

The vac tank hose that should be hooked to intake goes to also supply vacumn to evaporative carbon cannistor near vac ball tank inside left fender area above horns.

It is best that you find end of black plastic-like tubing that was hooked to intake port. It had a 90 degree molded rubber end on it originally and somebody replaced it with that fabric covered hose.