4052836-Right knuckle casting
04052838 KNUCKLE
04322294 KNUCKLE ASSY
04407954 KNUCKLE ASSY
04052840 KNUCKLE
04322648 KNUCKLE ASSY

4052837 - Left Knuckle casting
04052839 KNUCKLE
04322295 KNUCKLE ASSY
04407955 KNUCKLE ASSY
04052841 KNUCKLE
04322649 KNUCKLE ASSY

The numbers you originally provided are for the casting only. Give the dealer these numbers and see if anything happens. I can't get any more detail than that. So hopefully only one works and it is the correct one that you need.

4273100 is just the casting number for the 4273099 manifold according to the system.

5203750 looks like a newer number or a fastener number. It might actually be a number assigned to some aftermarket made exhaust manifold that Mopar buys and rebadges. Whatever it is I can't find it in the system. Sometimes mopar did make their own numbers for their aftermarket purchased stuff.