Looking in my original from 1968 Dodge, Chrysler, Plymouth parts book. Those two part numbers do not appear. It could be that the numbers might be for the 70 bodies, but its the same part. I put a standard 120 mph instrument cluster from a 70 Coronet into a 68 Roadrunner and worked fine. I noticed that part number 2822873 could be a misprint. That 7 could be 9.
The correct one could be 2822893 which is the in the 68 parts book for Dodge and Plymouth b-bodies 120 mph speedometer.
The part number that ends in 500 is not even in the parts book. I have 2 68 to 70 instrument clusters; one of the has a part number like yours and the other has a different number than yours.
The only numbers that are the same are the 65450-1 and 65460-1 just like yours. Maybe those are series numbers.
Don't know why the part numbers would be different for the same part. My point I guess is that that there is more than one part number for this assembly.