can i use a 97 saturn sl tranny in a 99 saturn sl

No they will not... Unless you have a car with a manual transmission and are swapping in another manual transmission, then you can use any S-series transmission, 91-02. Now if you have cruise control, you need to keep the same transmission that the PCM needs, or else it will not work with the different gear ratios (See: http://www.differentracing.com/tech_articles/gearratio.html)

Now if you have an automatic transmission, youd have to choose the correct transmission that goes with your car. Again, refer to that website: http://www.differentracing.com/tech_articles/gearratio.html. Or else youd have to swap pcms. Its a lot more complicated than David knows...

The number of gears in those transmissions are the only difference. They never changed to gear ratios in a Saturn.

I had a 94 Saturn DOHC, my son wreaked it and I bought a 95 SL1 . I put the DOHC motor & automatic tranny in it ,but the trans will not shift out of low gear. If I change the computer in the car will it work right & shift . I know the computers are different plug in' S. But can I cut the tabs off & then plug the computer in . I don't wanna have to pull it back out & change the tranny ,gotta be a easier way . Any help would be very appreciated . Thanks