I bought a brand new 48 in (I think) 1993. It was ordered in by a shop, for me.
It was exactly the same as the 52 at the time, but had a plain stock.
The cylinder was etched "48/52" and it had a TO1 trigger.
My mate had a 52 at the time.

Another model that was brought over here, not sure of date but possibly in the last 10 years was the 52 Ultra Carbine. I bought one (bought as a .177, but it came .22)
Very rare to find one in .177. Pretty much only .22
I was told that the .177's that did land over here, were sent back and replaced with .22