You want to look for the 91-92 magnum ones. These have the larger 2&1/2" exit. 93 up the PN changes and they use a smaller 2&1/4" exit.
72-76 A body 340-360 LH manifolds are a bit easier to find than the 68-71 340 ones. I found a set of those 91-92 dak ones in my local boneyard but passed on em because of people showing pix of power steering box clearance issues.