92 is around the time the tranny went from mechanical to electrical sender for the speedo.

you can try to pop or unscrew the cable of the speedo to the tranny.

on my 90, it's mechanical end has a gear end.

one more thing, there is a tranny throttle kick down cable that needs to be adjusted.

before i had my engine block swapped out due the head gasket issue, i brought my truck in to the dealer since i had DONE everything to fix my slipping issue.

on the freeway, cruise control on and suddenly, the tranny would shift down by itself.

the head mechanic at toyota told me about it.

cable goes from the throttle assembly to the tranny. and it needs to be adjusted in MILLIMETERS.