genISD

My idea was to build grey tender using battery box from 810.

Hello This is my first post here. I got 7715 from my childhood and just recently by a luck I got complete 810 motorizatioon set which can be used with 7715, according to instruction sheet. However I have no idea how to put battery box from 810. It's almost 7 studs wide (6 studs plus half a stud on every side - battery box thicker cover. I think I must build additinal train car from this battery box but grey is not so good looking. Have you ever tried using this approach?