I did 1157 amber LEDs on the front of a '97 GMC truck I had. The light output wasn't quite as bright as the incandescent bulbs, but it was close. They were in clear housings.
Only place I've ever got LEDs that I wanted to matter, was from SuperBrightLEDs.
Here is a link to what I used on that truck.
1157 AmberThis was a few years ago, and there are many more options available now. Look at your mounting depth, and how the socket is arranged (directly in the back, to the side), and do you have a reflector in the light housing that radially mounted LEDs could shine off of. You could also stick in some alum foil to reflect light from the backside.
2005 2500 Cummins/48RE/3.73, QCLB, 4wd, BigHorn, Edge Juice w/ CTS + Turbo Timer,Transgo Shift Kit ISSPro Oil and LP pressure gauges, GDP 20/2 filters, Custom Diesel Steering Box Brace
'10 Forest River Shockwave Toy Hauler 21'
Honda EU3000I Genny