In case you have trouble with the size labels the German Army use, I found this on an Evil bay sellers listing for the flecktarn parka.
Gr Nr.1 = Height 5'4" / 5'7" - 35.5" Chest
Gr Nr.2 = Height 54 / 57 37.5 Chest
Gr Nr.3 = Height 54 / 57 39.5 Chest
Gr Nr.4 = Height 54 / 57 41 Chest
Gr Nr.6 = Height 57 / 60 36 Chest
Gr Nr.7 = Height 57 / 60 37.5 Chest
Gr Nr.8 = Height 5'7" / 6'0" - 39.5" Chest
Gr Nr.9 = Height 57 / 60 41 Chest
Gr Nr.10 = Height 57 / 60 43.3 Chest
Gr Nr.11 = Height 57 / 60 - 45.3 Chest
Gr Nr.12 = Height 60 / 64 37.5 Chest
Gr Nr.13 = Height 6'0" / 6'4" - 39.5" Chest
Gr Nr.14 = Height 6'0" / 6'4" - 41" Chest
Gr Nr.15 = Height 60 / 64 43.3 Chest
Gr Nr.16 = Height 6'0" / 6'4" - 45.5" Chest
Gr Nr.17 = Height 64 / 67 39.5 Chest
Gr Nr.18 = Height 6'4" / 6'7" - 41" Chest
I hope its of some use.
Gr Nr.1 = Height 5'4" / 5'7" - 35.5" Chest
Gr Nr.2 = Height 54 / 57 37.5 Chest
Gr Nr.3 = Height 54 / 57 39.5 Chest
Gr Nr.4 = Height 54 / 57 41 Chest
Gr Nr.6 = Height 57 / 60 36 Chest
Gr Nr.7 = Height 57 / 60 37.5 Chest
Gr Nr.8 = Height 5'7" / 6'0" - 39.5" Chest
Gr Nr.9 = Height 57 / 60 41 Chest
Gr Nr.10 = Height 57 / 60 43.3 Chest
Gr Nr.11 = Height 57 / 60 - 45.3 Chest
Gr Nr.12 = Height 60 / 64 37.5 Chest
Gr Nr.13 = Height 6'0" / 6'4" - 39.5" Chest
Gr Nr.14 = Height 6'0" / 6'4" - 41" Chest
Gr Nr.15 = Height 60 / 64 43.3 Chest
Gr Nr.16 = Height 6'0" / 6'4" - 45.5" Chest
Gr Nr.17 = Height 64 / 67 39.5 Chest
Gr Nr.18 = Height 6'4" / 6'7" - 41" Chest
I hope its of some use.