I am trying to put my beast together again. This time i am using a th425 from a 1977 eldorado. I have a 3500 rpm stall converter with antiballon plates. I bought a new manual valve body with a trans brake off e-bay. I asked before i bought if it would work and they sayed yes. I was getting ready to install it but it's too small. The valve body that is. Has anyone used an after market valve body on a th425? Also what does the electrical hook up on passenger side near the vacume hook up do?

The electrical connection is for third-to-second kickdown. There has to be a switch mounted on the throttle so that at a certain point in the throttle throw the trans will downshift into second for passing gear. I don't know much about the valve body, I thought that TH400 internals worked for the TH425.
On another note, that converter has a pretty high stall speed, seems kind of high for a relatively light car, assuming this setup is for a Fiero.
BTW, I have a TH425, Diff and new converter for sale if you are interested.

Since i can't find a manual valve body that will fit i am going with a shft kit. This will let me do about the same thing but no trans brake. So i think it's safe to assume that i will not need the kick down electrical switch. That being it will not shift unless i move the shfter to another gear. I thought the stall converter was a little high also but i got a realy good deal on it so if it don't like it no big deal. Also at near 3500 rpm's i am starting to get realy good boost around 12lbs. thanks tony for the info. As far as parts all i need right now is a set of axles that fit the 425 so i can machine them down to fit.

No problem. A question regarding your swap: Are you going with the tradition setup where the engine faces forward or are you attempting the reverse rotation swap where the trans is forward of the engine thus putting more weight ahead of the rear wheels? I'm asking because if the latter is the case with your swap, I may have some axles you could use. In fact, either way you set it up, the axles I have may work or could be adapted to work with your setup. If you're interested, PM me, I'll be more likely to see your reply that way.

My old 325 was a forwad facing setup. I had no problems with it at all in handeling aspect. It's no autocross but for the street or drag it has great traction. so i will likely go back to forawad facing. I say go back to because the transmission mount betweent the 325 and 425 are way different. So i will be doing some cutting and welding to make new mounts.