for the speedometer,you may ned to replace the dash cluster.as for the transmission,you may want to check your fluid level,if it isn't low you may need a transmission servise,ie. change tranny filer and fluid
You need to replace the speed sensor on the rear of the transmission.
how u take off a transmission speed control sensor on a 1996 chev lumina
A 1996 Chrysler Town and Country does not have a speedometer or odometer cable. That signal comes from the transmission output speed sensor.
Check the speed sensor.
where is the turn signal flasher on a 1996 lumina sedan
sprak plug wiring diagram chevrolet lumina 1996 3.1
It measures the speed of the output gear of the transmission. It is used for shift timing.