Where to hook up Vac. modulator on 91 tbi chevy

[nckrawler]

i have a 91 tbi chevy that i put a 400 turbo trans in and dont know where to hook up the vacuum modulator valve
any help would be greatly appreciated

and i cant put a "T" in any of the existing vacuum lines b/c it trips a check engine light

 

[transman731]

It needs to be hooked to manifold.vacuum.(below the throttle plate)
Does the brake booster. Vacuum go to the tbi or the manifold?
If it goes to the manifold you can "t" into it