I speculate that those Tigrs that start with 78 belong to this 10th GRU brigade, because here is one that ends with 51.

http://www.yuga.ru/photo/polosa/1126.html

Little history http://www.ww2.dk/new/army/gru/10obrsn.htm

http://m.youtube.com/watch?v=aOWpormfMI8