Not the same relay as the horn but is the same type as the power window. If not too concerned about looks since it's under dash, modern such as thesehttp://www.parts-express.com/wizards/searchResults.cfm?searchFilter=relay%2012%20vdc and also available at most parts stores will work nicely. You should get one able to carry 30-40 amps.
This Post was from: https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?post_id=96954