It has the T-2 transmitter/SC3 receiver. The handset is dated 12-58 and the caps are dated 1-59 and the caps were difficult to get off. I got some Zap hand soap from work. This soap is in liquid form and has a gritty feel to it. It used it on the threads and rinsed it off when I was done. My dad would've said that I lapped in the threads with this stuff. Anyway, the caps are easier to remove now.