Turbo 400 experts please step in....

[joespanova]

Originally Posted by Mark Ugrich

You are partly correct. The tube was necked down to locate it to the fittings. This allowed for just a straight short piece of rubber vacuum line to seal the connection. If you look closely into the opening of the tube, you will most likely see a restriction on the end by the modulator. I would open up the ends of the metal line with a drill of appropriate size.It’s possible you may have to change the 1-2 shift valve spring in the valve body to get the trans to shift where you want it to.

Thanks.