Taken from http://www.mazdas247.com/forum/showthread.php?t=122622:
...replacing the taillights is a piece of cake. Open you hatch and there are 3 small round covers that pop out that reveal 3 bolts. Unscrew those with the utmost care so you dont drop them into the care. pop the taillight out, swap in the new reverse steps 2 and 1.
I would add that if you're replacing the passenger side bulb, you there are only 2 small round covers, the third screw is inside the storage for the jack. Also, popping the assembly out to access the bulbs might require a little more force than expected; as long as you have unscrewed the three bolts, do worry about breaking it--it will pop off.
help
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On a 2003 Mazda Protege it must be changed at 105,000 miles. This is an interference engine and as such if the belt breaks serious engine damage will occur.
no it will not fit.it is not the same lenght and the same height
1964-2003 and after that evolved into the mazda3
location cylinder 2 mazda protege
195/50/r16