I used a one piece fel pro gasket meant for a 2000 Dodge 360 magnum like the one kerndog had on my 75 360 la, fit perfectly, no leaks.
This solved an ongoing problem I had finding the traditional gasket with the proper rear rubber seal, all the ones I encountered the rubber seal was a quarter inch too long and would squeeze out when tightening down the pan. Problem solved
Thanks for the info guys!