Maybe I just need more coffee.....

There is a warrant in debt filed in the judgment book of the record room, (judgments good for 20 years)  the judgment was recorded in 1996.  client wants me to find out the unreadable case number of the  judgment, so I call general district court where the case originated from and they said they destroy all files after 10 years, that ALL their cases expire after 10 years (10 year judgment?), so I guess my question is, I reported this judgment because jugdments are good for 20 years, I dont feel comfortable telling the client the judgment is no longer valid, or am I thinking too much into this and the judgment is expired because of the general district court 10 year rule?  Isnt the whole reason behind recording your judgment in the record room so that you have 20 years to enforce it and possibly get paid for your judgment?