Heater and A/C vacume lines

[Motor City GMC]

First i have to say thanks a bunch!! This has helped me out tremendously!! And secondly, this should be my last question...Do you know the size of the line that is the main line coming in the cab from the "tank"? I know that it is gonna be smaller that the one feeding the tank because the nipple is smaller, but is it the same size and type as all the rest under the dash and inside the cab?
Im thinking mine has been jerry rigged at some point because coming off the tank is a clear line that is larger than the ones inside, but it comes off the tank and threw the firewall and then is reduced (by electrical taping together) down to the same size line as the rest inside the cab before heading to the control unit.