Oh Boy, I was going to multi quote but it was getting too long.
Automotive LEDs have a relative higher Resistance than a light bulb. This causes less Current draw in the system. Current=Volts/Resistance (I=E/R but that's confusing )
Less current draw, less wattage. less wattage, Less heat. Watts=Current x Voltage
I say relative because there has to be a higher resistance it or it will draw so much current it will burn out.
I've smoked many a LED myself. Once you let out the magic smoke, electrical devices stop working.
Getting back to the flasher,
The typical CJ Flasher has no coil in it.
Just a bi-metallic strip that bends when it's hot enough
It's designed to be in series with the whole turn signal circuit.
When a turn signal is activated current flows through the flasher and then the bulbs in the TS and the light comes on.
As soon as the current flows, the bi-metalic strip begins to heat and bend.
Once it bends enough, the circuit will open just like a circuit breaker and the light goes off.
When it cools enough it makes contact again and current starts to flow and the light comes back on.
and so on ad nausium.
Newer cars have current sensing circuits.
If a bulb burn out, the whole circuit draws less current. The newer cars sense this drop and flashes the remaining light faster to warn you a light is out.
If you put LEDs in a newer car, the circuit thinks a bulb is out because of the lower current draw. So it flashes faster.
But we are talking CJ's here so forget all that you hear about LEDs in newer cars.
If you put LEDs in a CJ, you will need a flasher that works at low current. It's simple and works.
You could put in bulbs or resistors but then you negate the advantages of LEDs.
By the way, even though the TS and parking light share the same bulb, there are two different filaments inside.