88 300E waterpump kaput but I'm puzzled...

I've been perusing this great site and I've seen some excellent posts on this subject. I'm planning on doing the job this weekend (with my neighbor's help..ASE mech..)hmm let's rephrase this ...my neighbor's going to do the job this weekend while I stand there watching.... anyway, to make the job easier I was going to have him get the FLXM 13 Snap On tool mentioned in the other posts(if he doesn't have it already). From the other posts it appears this tool has a 13mm socket on the end? I'm puzzled because my H20 pump has what appears to be allen head bolts holding it on??? From what I can tell I do have the new style water pump. Am I missing something here?

Also any advice on this job such as pitfalls to avoid? My neighbor's a pretty accomplished wrench and has done a few of these but he doesn't concentrate soley on Mercedes so any advice would be appreciated! Thanks!

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88 300E (plus used to have 72 350SL, 83 240D)
Dad's got a 99 ML320 & 93 300SE...we're a Mercedes family !