It should be towards the bottom front of the tranny on the passenger side. There should be a vaccuum line running to it. I'm not sure wether the one you have screws in or there is a clamp holding it in. You should be able to tell by looking at it.
it's on the passenger side of the car above the pan rail on the right rear corner above the transmission crossmember it has a vac hose running to it.
Be careful,,,, When you pull it out, there is a rod,pin, that is easy to lose. I'll be corrected if I'm wrong, nut I think the c-4 has it. Good Luck!
Thanks for the pic, the auto store gave me one woth only a single vaccuum line, I was going crazy, the one in the car has 2 coming off the side of the modulator