Divorce info
If it was done the same way in 1988 as it was done in the 1990s, then if someone (anyone) goes to the local registry where his marriage was first registered and obtains a copy of his marriage certificate, there should be an annotation at the bottom recording the divorce and the sentencia. From that he should be able to find the actual decree at the registry where it was first registered. He probably knows where the divorce was first registered.
Good luck.