smoking bad need help!!!

[muscletruck]

hey guys and gals i need some help... my truck spews white smoke when i stop after having the motor at a steady cruisen speed (freeway)... at first i thought it was rings... but i noticed my tranny was losing mass amounts of fluid after i drive on the freeway... so i think the vacuum is sucking fluid into the motor... woudl this cause white smoke?? because i put in about half a gallon of fluid... cause it was slipping and shifting all over the place.. i put the fluid in & ran great!!! i checked the fluid and it is low again... in the tranny ..mind you the pan doesnt leak... so i need help ya'll... if it is the tranny do i just put on a new modulator?... thanks all... oh ya.. by the way 454/TH400....thanks again

[Chevy67Tk]

Yes and yes

Yes burning trany fluid will make a white colored smoke

And

Yes if its not leaking on the ground you are probably sucking it threw the modulator valve. They are fairly cheep and easy to replace.