Just curious if a 91 do series auto tranny will work on a 97. I know the 5 speeds wouldn't because of cable and hydro clutches but no idea if there is a difference in the autos and all info like this I have been able to find online so far is dealing with 5 speeds.

Just curious to know if I have a spare ornot for my girlfriends new civic

 

no it will not. 91 is self hydraulic controlled with a cable from the throttle. 96-00 is computer controlled. you would throw a ton of check engine / D4 codes if you swap it out if it works at all. not worth it IMO.

 

Nope, it needs to be the same as what came out, even the 3 different D-series engines that came in '96 - '00 use different transmissions that aren't compatible with each other.