Front Turn signal - 3457 or 3157

I searched, even google. Seems to be a up in the air item. Front turn signal bulbs need replaced in my car. I pulled one last night, it was flaking amber, 3457. BMW owner's manual doesn't say jack crap about the #. Just a 21W dual filiment bulb. Closest match I've found is at Pelican parts. That's BS. I'm running a 3157A in it since yesterday b/c it's all I had at home and it works fine. I need a part # I can get at Autozone tonight so I can replace the set L&R. Thanks in advance.


Edit: The socket has 3457A cast into it. Guess that answers my que. So FYI for you all.

Edit 2: did some research on the bulb specs and there's not much difference between the 3157's and the 3457's. Which Sylvania has 3357/3457 on the same box. So in the end, the 3157's I had laying around work perfect. I'm leaving them. But if you have to buy new, i'd buy the 3357/3457 ones. Still don't understand what the differences are... that's probably why these companies have started making one bulb for multiple part #'s.