[nexium]

Crewzin - curious if the LEDs you used are the same as the ones in the link's picture. Also, do your lens assemblie have a smooth or "fresnelled" interior surface? I found not many sellers of the drop-in 3157's have any idea of the actual light output, or whether or not they will allow a stock tail/parking light assembly to meet FMVSS standards. Most dedicated LED lighting units have a housing designed specifically for LEDs and will not allow "backards compatiblity" with any other lamps.
The other snag was finding a suitable 5 pin flasher for the PT, to eliminate the burned out bulb rapid flash. You could modify the existing one, but if you're uncomfortable around SMD PC boards, that's pretty much out. The only other option is the load resistor fix.
I am glad to see your combination works, but can't believe that an end firing drop in with maybe 13 LEDs provides the same amount of visibility as an ordinary 3157. The ones we used were of the "tower" design, upwards of 27 LEDs, end and side firing, I presume in an attempt to used the reflector more effectively.