Sounds like someone has converted your rear turn signals to dual filament by installing front turn signals in the rear. You can install any kind of lamp that you can figure out how to mount and wire. If you want the running light option then look for a dual filament bulb like a 1157 (3-wire) or the 1156 (2-wire) for single element for no running light. Amber running lights are illegal in some states. Here in Florida it seems to be ok.
Led's have a problem. Your blinking rate may blink very fast or not at all. You can correct this by installing an LED flasher or by a load resister, (which will heat up). Your better of with an LED flasher. Some LED lamps are not very bright in daylight so keep this in mind. If you use an LED flasher then your dash bad bulb indicator will most likely not work. Meaning if a bulb burns out the flasher will continue to flash the ok bulb and the dash light will blink giving you no indication you have a bad bulb (no big deal). A load resistor will cause everything to work as normal. Not a big deal but wanted you to know. I would us an LED flasher as this would lower the current draw and help the stator if I went the LED route. Make sure the lamp you get does not require a ground thru it's shaft to work. Look for 3 wires for dual filament or 2 wires for single filament.
hope this helps?
!! Go ahead blame me ___ Everyone else does !!