Yeah, just looked at a pic of my car and its the one with the two lines going in it. 73 used a unique one year reservoir.
Here is the kit with the bottle (E body). I cant seem to find the kit I bought with just the cap, hose, clamp. It is available out there somewhere. BTW, the 73 reservoir is not available new....only the cap and hose kit. Fits 73 74 Challenger Cuda Barracuda E Body Radiator Overflow Bottle Kit NEW | eBay