5.9 Magnum into a 73Duster

On the pickup that cam with my aftermarket pan, there is a tab that is supposed to mount to a stud on the end of one of the main bolts. Being as the stock Magnum pickup doesn't cross any mains, there is no such stud on the Magnum engine. I ASSumed that there was one on the stock 360, but never having torn down an LA 360, I don't know for sure.

Can't say I've seen what you have.
I'll take a guess that your setup was designed using a windage tray, and those main bearing bolts have the stud, or a threaded bolt hole in the end that you need.