[onewhippedpuppy]

Originally Posted by Halm

Change over for both 3.6 and 3.8 was mid-year, 2005. There is a thread over on RL that has breakout of change based on engine serial numbers. I have it bookmarked on another computer and will try to post the link tomorrow.

Here's a link to engine codes and serial numbers as applicable to different models: https://dl.dropboxusercontent.com/u/93289189/Porsche_Engine_Codes_1952-2012.pdf

My understanding is that the M96 engines in the early 2005 997 and 997S are those with the replaceable IMS, and that anything with an M97 code is the non-replaceable IMS. The 987 only had an M97 engine, hence no replaceable IMS. But I have never seen a direct cross reference between engine code, engine serial number, IMS design, and VIN number, so without actually pulling the transmission I am not aware of any way to tell which IMS will be installed. But if you have an M97 engine or anything from 2006 and on, pretty safe bet that it will be the later IMS design.