The 15mm flex socket did the trick. The new problem is trying to separate the PS pump from the vacuum pumps, and the big gear. I'm trying to replace the leaky O ring seal that separates the PS pump from the rest of the unit. I have a factory service manual (diesel supplement), but very, very sadly, the entire chapter on the vacuum pump is missing (another great e-bay find). It appears that the big drive gear is pressed onto the PS pump shaft. The manual calls for special tools to remove and replace it. I thought this would be pretty straight-forward, but it's looking like a bigger challenge. Anything I'm missing here (besides a complete service manual)?
Larry