Belt tensioner replacement

How hard is it to replace a belt tensioner on a 99 Tahoe, 5.7? Anybody ever done it themselves? Also, I can get one from GMPartsDirect.com for $36.29. It has the GM part# 12456152. Can anyone confirm this is the right part number? I just want to make sure because it's a non-returnable part. Thanks in advance.

That should be the right number. Just use a 3/8 ratchet to rotate the old tensioner enough to remove belt. I think its a 13 metric head bolt that gets removed

Thanks for the help. I went to Napa and they had one in stock. It was pretty darn easy to replace. Took me about 5 minutes.