As far as I can tell from the book, the users just dumped the heavy original and used the 08/15 bipod without any alteration - hence my use of the term “plug-in replacement”. It happened in the field, where alterations would hardly have been feasible.
Perhaps somebody out there has a 08/15 AND a T-Gewehr, and can make a direct comparative measurement?
More realistically: it appears that there are some 08/15s in the hands of forum members, so the mounting could be measured and the results published here for that Randy to compare with the T-Gewehr.
Randy: why don‘t you just post an information request on the MG forum?