Looking for correct bulbs for 1965 Plymouth Valiant 200 for Instrument Cluster

^^Not only this above, but some LEDs won't dim properly in a cluster because they do not draw enough current. The dimmer is a simple variable resistor, known as a rheostat. The operation of it requires a certain "in range" load on it. EG if you were to go through the car and remove all the panel lights controlled by the dimmer, and put just one back in, the dimmer may not work well because of the reduced load

Another general issue with automotive style LEDs is that the light pattern simply just is not right. This is a big problem in tail/ park lights and reverse lights. Add that to the "china quality" issue.