Chevrolet Repair: 77 chevy TH350/ 85 350 engine, chevy silverado, vacuum problem

Question
i have a 77 chevy silverado, privious owner installed an '85 350 and pulled off most of the vacuum lines, my truck drives "mushy", i installed a new transfilter, and modulator but still "mushy" I'm thinking it might be a vacuum problem

Answer
Ok. If it has a TH350 Tranny there is only one vacuum line that goes to it. There should be a vacuum canister looking thing on the rear of the tranny. The vacuum line should run from there along the top of the tranny and come out under the distributor. It should connect to something on the intake manifold between the carb and distributor called a vacuum tree. There is usually two or three vacuum lines run to it. The brake booster should run to the carb along with the distributor if its HEI(the vacuum advance on the distributor). Other than that there really isn't any other vacuum lines on something that old. Get back to me and let me know if mushy means that it lags when you take off or if the engine is going pretty good but it doesn't seem to take off as good as it should. The tranny could be in need of replacement.