2-3 shift on an "A904-LA" question.

Turn up the line pressure on the valve body 1/2 turn. Install a part throttle kick down valve on the valve body and a lighter 340 governor piston in the governor on the tail shaft. All can be done in the car. You won't believe the difference.

If shifting manually with a auto trans pull out in drive then after the car is moving then pull it to low/1st. low gear is different in drive verses low gear in the 1st position when pulling out from a stop. You'll feel the difference when doing this. There will be no overlap and have a crisper shift. from low to second.

The pressure adjustment is the allen screw on the side of the valve body.