Classic/Antique Car Repair: vacuum modulator valve, cadillac eldorado, vacuum modulator

Question
QUESTION: i cant seem to locate where the vacuum modulator valve could be on my 1980 cadillac eldorado

ANSWER: I need a little more information please. What engine package do you have in the car? Does it have fuel injection? Is it a conversion from a diesel?
Brad

---------- FOLLOW-UP ----------

QUESTION: yes it is a conversion from diesel but she has the stock trans with a 73 olds omega 350 carburated

Answer
If the transmission is the original the modulator should be on the side of the case in front of the bell housing on the engine side of the transmission. Now to make sure that we are talking about the right transmission can you get me the codes off the tag on the transmission?
Brad