taillight???
 

I recently blew a rear bulb #1057 which local parts stores seem to have never heard of, is there a replacement equivalent or must bulb be purchased at dealer?

any major auto store should have a replacement. Be sure it's the bulb and not the contacts, though.

Replacements (dual and single): 1156, 3156, 3157, 1157, 1034, 1142, 2057,3496.

And I believe also: 1034 1076 1130 1142 1152 1154 1157 1158 1493 2057 2357 2397 3496 7528 (single and duals)
Compare the base to make sure.

So is it safe to assume the the #1057 on the original bulb is just for the dealer and these other # bulbs will work properly also?

I believe that the #1057 is the same as a PY21W. What year is your X5? The key is the offset pins. This # is good for the turn signal, since it is amber.

1057 older version, other bulbs will perform the same.

model year is 01 and thanks for the info. I tried one of the #s suggested and it seems to be working fine. Thanks again.