“PermaDry”Timing cover gasket
I have used the Fel Pro blue gasket that comes in the sets and I think I got a Mahle or Victor Reinz set once also. No troubles with any of them.
The current Mopar part number appears to be 53021057AB and it is a different material from the others, but I have not tried one yet because they are more expensive.
Also, what year was your Magnum? Just curious.