5th gear pops out of gear
 

hey, im looking at buying a used 2000 2.5rs MT, with 138k miles....the owner says it has a problem with 5th gear popping out of gear while on the freeway...is this a indication of something serious, or can it be easily fixed, and how much would it cost to fix? i dont want to buy a car and then have to buy a whole new transmission for it

Very common reported problem in the UK.
Happened to me.
The nut holding 5th on comes loose.
Can be fixed (tightened) with box in car, but it is a large nut inside the rear of the box.
A Subaru dealer will know all about it.

Graham