Looking forward to seeing this develop. Went to Eberbach in 1969, class 050 from Erbach, the branch, and 065 001 on the return. Most trains from Darmstadt terminated at Erbach.
From memories it was a V200 from Eberbach to Heilbronn. There were steam workings from Heilbronn on the line including 064.
There was a yard in the area between the main line and the branch which contained what looked like old narrow gauge stock. No other info, it’s 50 years ago.