I am a bit confused about the connection between your citation of my post* and your question.
AKG used several transformer types and manufacturers for its large diaphragm tube mic transformers over the years, and each is of course "original" for that type of mic. But I found that some types do not readily interchange with others in AKG mics (hence your cited passage of my earlier post):
Despite its technical shortcomings the T14/1, for example, is the only transformer which retains a balanced frequency response and exciting timbre in AKG's ELA M mics. Likewise, an old Henry version in a late model C12 is not a symbiotic match either, due to the different capsule versions used.
* I just re-edited the wording of that old post because a whole line of text had been deleted in a previous edit. But the original message of that post remains the same: the less than ideal transformer (T14/1) is the original and only one I would recommend to use in the ELA M250/251 in order to retain the mic's spectacular sound.