aumsc400

I've done numerous searches and can't really get a clear answer. I have a 97 sc400 and from what I can tell up to 97 they had the 4 speed tranny and changed over to the 5 speed in 98. On the 97 to adjust the transmission line pressure do you do it by tightening the transmission cable at the throttle body or turn a dial on the valve body? This is where I'm confused....I get the feeling that the valve body screw adjustment is for the 98 and up 5 speed autos. Anyone that can let me know I'd really appreciate it!