Dash cluster Signal indicators

I recently replaced the dash cluster in my 74 duster with the classic industries blank cluster and gauges I picked out. I got it all in and realized I had overlooked signal indicators. I’m curious what has anyone done for their dash when replacing the stock cluster? I’m thinking a couple LEDs something simple. Also if I’m reading correctly the circle pin connector will need to be tapped to make that happen and would explain why since unplugging that my signals now just go solid when I hit the switch or am I assuming wrong ? Open to ideas and experience.

Since you didn't change the wiring, I assume you are just missing the two bulbs and holders that twist into the back of the circuit board.

Seems to me that the two 1157 bulbs along with the fender mounted would be enough load to operate the flasher. I have driven a 67 without its inst' panel and the signal flasher did work. That model doesn't have the added fender mounted either, so my 1st suggestion... a new flasher wouldn't break the bank.
If that doesn't cure it, check for good 12 volts into the flasher and check the chassis ground paths at all exterior fixtures from inside wall of bulb socket to battery neg'. You might have stumbled onto a weak exterior lighting issue that was already present. We've seen cases where flasher didn't work at switch on/battery alone but would work with engine running/alternator output.
In the end, If you still need the additional load of the #158 indicator bulb to operate the flasher, the very low load of LED probably wont get you there.

When I did my dash I bought 3 small LED's, two for signals and a high beam indicator. They were very similar to the ones in this link but I can't find the ones that I bought. But they work great!

8mm 12V Concave Metal Indicator LED Signal Lamp Light w/Wire Lead Green | eBay