How to replace the belt tensioner idler/pulley on '89 Lesabre

I need to replace the belt tensioner pulley on my 1989 Buick Lesabre. I've replaced the belt and alternator in the past but never removed this pulley. I have both the Haynes and Chilton manuals and there's no mention of removing the pulley. Thanks in advance for any advice you have to offer!

On '87 it was a reverse threaded bolt, which means turn it right to loosen. It is normally turn left to put the belt on. Someone told me to loosen it just keep turning left, so I got out a pipe and put a lot of force on it, and I twisted off the bolt! I had to get a whole bracket from the junkyard! So turn right to loosen it.