Tried to go to the dealer for parts

The guy at the counter says the computer will not let him look up anything before 1984!

Does this guy not know what he is doing or is this the norm?

Why I went there:
I was looking for a lower balljoint to spindle bolt (unique head/length not available at hardware store) I was able to look up a diplomat to find the bolt only to find out it was no longer available. Interesting to me was the bolt was used in the 50s on up to 1989.