Identity of Lufthansa's first in-service 737-130??

I’m currently working on a book on the Boeing 737-100/200. I’ve been scouring the net, every book I own (which is a pile), and have contacted Lufthansa directly (no results) trying to determine which exact LH 737-130 flew the first commercial service in 737 history on 10 Feb 68. Given the historical significance of that flight, you’d think somebody somewhere would know what airplane it was that flew that first flight.

I know that 737-130s D-ABEB and D-ABEC were delivered together on 27 December 67, and that in all likelihood it was one or the other of them, but as I say, no luck pinning it down.

Anybody? Any assistance greatly appreciated!

Thanks!

J