I have a 1998 land rover discovery and ive replaced the alternator and the battery and the car keeps breaking down. first the radio goes out and then the lights dim and the srs light goes on while it is still running. then about after five minutes the battery light goes on and then the car wants to stop running.

You'll need to check with the dealer to see if your voltage regulator is in the alternator or in the computer. If it is in the alternator and you bought a rebuilt unit, it is possible you have a faulty alternator. Check with the dealer first as to the location and then remove your alternator and have it tested. New alternators usually cost more but there is less possibility of faulty components inside. If your regulator is in the computer then you are in for a greater expense in replacing the computer.