Is there a difference between the 96-98 GT upper plenums and the 99-04 plenums? For that matter is there andifference between the TB's as well? I know all about the 99 and up PI heads and intake, just curious about the Upper plenum and TB.
The PCV valve connection into the upper intake on the front is a little different too btwn pree 99's and post 99's... so if you get a new upper intake, make sure it has both options (my accufab came with both)
the only real difference is the vacuum lines. I Port these things for people and have seen a a few different casting styles inside. some of the 96-97 styles have tiny vacuum/pcv lines and are a horrible design, most of them have a hump in the back, i've had a couple that didn't. but basicly they are the same.
I'm kind of just getting into the Mod motor. A 5.0 man you know. But I bought a ported plenum with a 70mmTB. I don't know what year Ford changed the size of the valve, I'm guessing it's the PCV, but his was a lot smaller than mine . I have an 02GT. I''m glad I had only taken a few bolts loose before I actually installed it and noticed it. Maybe someone with a more extensive 4.6 background can tell you what year the change occured.