Turn signal switch for 71 Dart

Hey guys. Just before Christmas last year I picked up a '71 Swinger Special. It's a little rough around the edges being a northern car but it's got good bones, a strong running slant six and a pretty nice interior. The first day I had it I corrected a long list of little issues and daily drove it until couple weeks ago. I was making a left turn, felt something snap and then the blinker stalk just kinda hung down. Pulled the steering wheel, ordered a replacement turn signal cam and got back to it. One day my mom was visiting and pointed out that she never saw the brake lights when I was moving the car around my property... apparently my wire splice job was no good. I tried to fix it but didn't have enough wire left to work with so figured I'd just order a new turn signal switch. (I suck at everything to do with wiring.)

I ordered the OER one which specifically says it's for this car. What arrived looked similar but not exactly the same as the switch I removed. I figured it was just simplified manufacture and went ahead with the install. As soon as I plugged it in the rear flashers came on (only the rears). Everything else worked like it was supposed to. I called the supplier and he sent another switch out which does the same thing but also the left indicator won't turn off. Interestingly, today while searching I saw an E-body guy describe the same rear flasher condition with what I assume is the same switch. Frankly the overall quality of the OER switch is not impressive, with flimsy plastic and overly stiff wires that have too much slack.

I figured both of these switches were faulty and started hunting for a replacement. The switch I removed seems to be P/N 3488804. The only ones I can find for sale seem absurdly expensive so I was trying to figure out if any others interchange. The one for the 73-78 truck looks identical but has a different part number, 3635505.

Anyone else been through this?