GKD,
I take it you mean adding Adsense like it currently appear on this site. The mod for that is this:
I was told by one of UK WW members that the best adsense inside a post is this one:
Google Adsense Postbit Integration - vBulletin.org Forum
You can also add adsense to user profile, the mod for that is this:
Ads Inside members profile - vBulletin.org Forum
Good luck.
GKD, I will also suggest you update your vB, a few important updates has been added since the current version your run.