I am talking about 105 SC, rather than the earlier 1050 (the 6 speed, later 7 speed, that I had on my first proper bike), or the even earlier 105 Golden Arrow.The first 105 was 6 speed, I had the gear set
Thank you...I have been offered a six speed Exage threaded freewheel so may use that instead of the Suntour ultra 6.1055 and 1056 are the same groupset. 105x is all 105SC - the first iteration was 7 speed, then 8 speed, which updated the derailleurs and shifters (1056 not 1055), but not the brakes. The triple components are named 1057 - not newer, just a variation.
The biggest change was the rear derailleur, which is cosmetically quite different, but seems entirely interchangeable.
(I currently have 4 groupsets worth of 105SC and 3 of RX100 in the workshop, so am quite familiar with it).