Some 235's have a 1/2" pipe thread in the intake just below the carburetor flange, bushed down to a 1/4" vacuum line for wipers. It's simple to install a bigger fitting to supply the vacuum if you have that setup. If the manifold is not drilled and tapped for the big pipe fitting, either enlarge the hole and rethread, of find another intake with the big hole already there. I'd reccomend removing the manifold before the drill/tap operation to keep metal shavings out of the intake!
Jerry
