It is 1110, light tan. The 1109 is a dark or gray buff. More importantly (I just found), the design is different. Same pandas but with clear differences in the overall design:

(Not my stamp, which itself is a torn reference item)
Nice contrast to the mostly garish issues of the period. I also recall the later horses set and cartoony pandas were black and white brush-painted designs, but they should have made even more issues using this style of artwork.
It's the same here regarding complete sets. What was sold in variety stores and even in stamp shops were short sets, so that's what we find in collections today. It was what I could afford as a kid. I don't mind playing catchup today. Still, completing sets is not the major target these days even if I could afford it.