When you remove the modulator, there is a black pin about an inch long and 1/8" in diameter. It's so easy for that pin to get lost. That pin must be reused with the new modulator. Without it, the transmission won't shift out of 1st gear until you reach a ridiculous speed.

I suspect the guy who first did your tranny lost that pin. Either that or the vacuum line was totally destroyed by the tranny fluid being sucked into the line.

It's probably best if you check both yourself. The modulator on the 3.0L is a piece of cake to remove. One single retaining bolt on a clamp (similar to what holds down the distributor, but much smaller) and you can pull it straight out to check for that pin.

Also, check your fluid level since you do lose some fluid when you remove the modulator.

Good luck.