Are you sure of this?? Maybe the previous owner changed them from stock setup??
1157 has two filaments and offset locking pins. 1156 has one filament and matching pin locks.
If your turning signals stay on, and glows brighter when turning, then I'd think you have an 1157 type bulb. If it only comes on when you select the direction, then 1156.
Either way, if you like the signal rate and the self canceling flashers, you'd have to put a load resistor in line with your LED replacement bulb, or opt for a separate flasher relay that does not rely on resistance for its flasher rate.
I used these on my tail. Since they did not flash or self cancel, it was an easy upgrade. Just had to make sure the polarity was correct..
The tuning signals were a bit of a PITA, because you need the correct polarity AND resistors. I opted to stay with the regular bulbs for turning.
I think I got these on Ebay. Price was decent.. something like 10 for 18 bucks or so.