I've got a 1956 dated receiver/rifle numbered in the 77Lxxxx. It's not pristine but still pretty nice. The receiver was obviously replaced at some point. We've discussed this before here. I also had a 1956 dated receiver with a C No.7Mk.1 barrel installed as described in this thread. I've since built a C No.7 using a proper original surplus receiver so I've got the '56 date receiver set aside for a future project.