My 2000 saturn sl2 doesnt go in reverse. could the fix be a nut that is behind a plate in the front wheel, drivers side

Famous problem for saturn, yes that bolt (output shaft) has come loose, and it only gets worse-You have to buy a new one, and get one for the input shaft while you are at it-saying that, I'll add some people get away with draining the trans (about 5 quarts) and remove the spin on filter, and refil with 4 quarts of Dextron III and one quart of a trans cleaner/solvent. Then park the car so that the rear of the car is resting against a wall, or telephone pole, something substantial and stationary-Put the car in reverse, and let it idle for 30-40 minutes. It cleans out the valve body (sometimes) enough so that the pressures are high enough to give you back some reverse-it worked for me (99 SL2, 178,000 miles)-You need to drain that mixture out after a short while and put in 5 quarts of Dextron and another filter (trans fluid changes are so easy in a Saturn, like changing engine oil-easy). If you end up doing the bolt fix, you should also do the valve body fix too, that is get a rebuilt one from one of the people who do them all the time-it is a little cottage industry and you can find them on Saturn car forums.