My sister has a 2003 Forester XS. She recently had to replace the driveshaft and replaced it with one from a 2002 Forester. Since she replaced it, she has problems with the seal in the transfer case leaking. She has also had problems shifting through a couple of gears. I'm wondering if the driveshaft from 2002 is a different length and is causing these problems?
If you're talking about the drive shaft going to the rear axel from the transfer case then it appears that the length of the two shafts according to the specs look to be the same.
Did someone change the shaft for her or did a professional mechanic do the job?
Was the shaft new or used from a salvage yard?
When ever you change any type of shaft that has a seal to be on the safe side the seal should always be changed even if the seal didn't leak before. This is just a precautionary measure so you won't have to do the job twice. The seal is not expensive and takes only minutes to change.
The shifting problem could be a coincidence but the two shafts should have been compared side by side to be sure they were exactly the same. Also the yoke (the part that goes into the transmission) should have been checked for wear and the point where the seal makes contact if the shaft was used. This could be the source of the leak if it is worn.
If you still have the old shaft, bring it to a repair shop and have them make a comparison of the two shafts while the car is on the lift. They might see something you may have not noticed before you put it in (if you put it in). The mechanic can also test drive the car to help determine if the shaft has anything to do with the shift problem or if the transmission is the real problem.
If you need any more help get back to us and we can look into the problem further.