See post #4 - link leads to a google search of Liddy appearances and mentions on the Stern show. Liddy was on the same stations as Stern in many markets during their time in broadcast radio - often back-to-back. I think Liddy generally took the pranking in good humor.
Liddy was a guest on Stern's show several times in the late 90s, usually about a book or calendar promotion - like now. Just heard he was on Hannity yesterday too.