I also have this... Packet 38 as well, but expected 163840 bytes extra
Diorite is stone 3:/fill <x1> <y1> <z1> <x2> <y2> <z2> stone 3 replace
See: http://minecraft.gamepedia.com/Diorite#Data_values
I assume this is related to the bug I reported... My situation isn't exactly commonplace, but it should be the same fix...
MC-44620
Also: MC-44531
I also have this... Packet 38 as well, but expected 163840 bytes extra