Good evening I'm a noob and I gots a question if certain pans are interchangeable according to the rule book? can I use link pin spindles on an IRS pan about 70 to 71 vintage

NO!

so the spindles must be used from the same year to year of the pan? not select for one to another

so the spindles must be used from the same year to year of the pan? not select for one to another

If it is a ball joint pan, you have to use a ball joint front end.
same with the IRS rear

Ok thank you does anybody have any problems with over extending ball joints

If you can, then do it.

Thank you so much for all of your input now I can start shoping for the required parts

What there saying is they can't be intercganged. two different animals.