its not leaking cant find any leaks where is the modulator located white smoke come out the tailpipe after starting the car its a 91 bonneville se

Sometimes white smoke out the tailpipe is actually steam from a blown head gasket.
The transmission'* vacuum modulator is on the front of the engine toward the driver'* side bolted to the transmission. It should have a vacuum line hooked to it. It is possible for the vacuum diaphragm to be perforated and transmission fluid to be sucked into the vacuum line.
Send a private message to opensourceguy, he plays with his a lot.
Also check for leaks where the transmission lines meet the radiator.
If you are losing fluid, it has to be going somewhere.

yeah my modulator went back on the old motor... smoked like one helluva blown head gasket. Clear a field with that. It'* probably the modulator... to test, pull it off [one 13mm bolt on a small bracket]. Disconnect vacuum line, and push pintle in... does trans fluid come out the vacuum line? If it does, it'* blown. Go to the parts store, and get one for a 93 bonne... it'* adjustable. Tighten that thing up... it'll make your shifts super firm [longer life], or loosen it up for super smooth shifts. And it'll get rid of your smoke.