^^^ Still valid.
Yup.
A 350 would have a kickdown cable, probably in the same place as a 700/4L60 would have a TV cable.
Yup--sort of. The vacuum hose would go to the vacuum modulator, not a "kick down". But the vacuum modulator can affect kickdown, indirectly.
He's said that there's a vacuum hose to the side of the trans.
Cannot be a 700 or 4L60, as they don't use vacuum modulators at all. (Significant design screw-up, in my opinion. Better to have a vacuum modulator for 95% of applications, and replace it on the 5% of supercharged vehicles with some sort of mechanical/cable TV arrangement, than to screw-up 95% of your applications with a TV cable.)
Cannot be a swapped-in TH350, as the vacuum modulator is at the rear, AND they'd use a kickdown cable.
Therefore, has to be a TH400-family three-speed auto transmission. They're the only ones with a vacuum modulator on the side of the trans.