Turn signal question

[1972CST]

I have been working on getting my 72 blazer up and running after being off the road for about 10 years and now its time to tackle the wiring. I swapped the idiot light cluster for a guage cluster and everything seems to work fine except the front marker lights in the fender blink with the turn signals in the front bumper. I did notice the lamps share power and ground but I dont remember this ever being normal. This occurs with the headlights on and off. The rear marker seem to function properly burning solid and not blinking. All exterior bulbs are new and correct. Thanks in advance for any help, Ben.