Yes, you can determine single or double row IMS w/o dropping transmission

I don't think this has been posted here before. I'm in the middle of dropping the trans on a 2000 996 C2 and just realized what I'm sure others must know by now. I've read that some can do it with a small bore scope, but not having one of those, it takes about 30 minutes or less to remove the cross member to get a good visual. Of course this assumes that you have original bearings and don't have a retrofitted one. You can see the flange pretty clearly just by removing a few bolts to determine whether the flange is "deep dish" (single row) or less concave (double row). See http://imsretrofit.com/what-ims-do-i-need/ for visual comparison to determine which is which. In the picture below: remove the diagonal braces by removing the two bolts (yellow arrows) and the two at the blue arrows (under the covers just forward of the rear wheels) Remove the collar nuts on top of the diagonal (not pictured) and pull the 2 diagonal braces off. Remove the 4 bolts/nuts (red arrows) and pull out the cross member. Ignore the black arrows. You should be able to see in the slot between the engine and trans to see the surface of the flange. Looks like I have a double row in this picture.

My memory of this is fuzzy but I seem to recall reading a post by Jake Raby that one can't go by the appearance of the flange. Apparently, if I'm not imagining this, a deep flange can be combined with a dual row bearing or vice versa. JR was adament the only way to be sure is to actually have the bearing in view, if not out of the engine.

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I'm not sure that's accurate. I can't see how a double bearing can fit under a deep flange in that space. I think the bearing kind of bottoms out in the IMS and the flange needs to fill the space between the bearing and the outside of the block. Again, this assumes that you have original bearings and don't have a retrofitted one. For what its worth, I'm pretty sure that I saw a post by the person you mentioned that said you don't need to pin the cams when doing this job. I'm sure most would disagree with that. https://rennlist.com/forums/996-foru...ml#post7290638

The flange tells the story 99.99% of the time. Out of 550+ IMSR procedures we've had ONE instance where a factory dual row flange was machined to fit a single row bearing. I documented that. The attendees of my "101" class last week learned exactly how to ID these, and verify them with the engine in the car, and without a bore scope in most all manual 996s. Tips are a different story.

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The photo above and the instructions I posted are actually for a tip.

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The 996 saw two manufacturers of the Tip tranny.. Of those there's at least 4 different bellhousing varieties. These lead to some fairly significant variables in regard to what can be seen in the IMSB region.

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Good point, but in reality only the 2000 and 2001 models are the ones that are in question as to single vs double and they both have this same transmission. The above is a 2000 C2.