I hoped, it was clearer to me now, but I can only say, I'm more confused. I was looking in the World Sports Car Racing Page, and found out, that the SF used minimum 20 6C 1750 GS-SS for Racing, some 6C 1500 SS and even an Austin Seven. Apart in Grand Prix Racing, they had a Duesenberg, several Bugattis and the two Maserati CM and I'm shure, that each Car had an SF Number. I can't believe, that the SF Numbers were only for the 8C 2300 Models. I think it was only a Number, for mantainance Record, to identify more easy the Cars. Maybe only the Cars, which the SF built new, from used parts, recieved the SF Number stamped?
The Scuderia was more a rich Peoples toy, with backing from Alfa, cause this Guys bought a lot of stuff 11 8Cs from the first Series of 50 Cars, not bad, apart several 6C 1500 and 6C 1750.
I think the buiseness for Alfa was, they produced racing cars, the Scuderia bought, developed and raced them and the Credit went to Alfa, it only went wrong, when Alfa startet loosing Ground against the Silver Arrows and the Supercharger was banned, from most Sportscar Races. There were left only the MM, LM, Spa and some local Races. Italy was banned from most European races and in generall, there were no buyers for expensive Sportscars. Lucy Schell put the money to Delahaye, to produce 16 Speciales. Tony Lago, made six Cars and sold only two. Amilcar made two Pegasees and transformed one to Streetuse, with Figoni Body. Maserati did a Handful of cars, Bugatti could hardly sell some. He had to use the 54 and the 59 as Sportscars. England absorbed most of the Cars. I think to Germany , went only 4 Alfas. Mercedes bought one Monza and a Tipo B, for Carracciola and Paul Pietsch bought a Monza. A single 8C 2900 B (412.021) went to Germany, was stored during the War and 'liberated' afterwards by one American Soldier.
I think, thats what happened to the 8C 2900. No buyers, they had to transform them to Racing Cars, for the MM and later again, back to Street use, with new numbers, cause the buyers wanted a new Car and not a Race prooven.
To avoid Taxes, they used the Old Numbers again. Alfa sold even after the War some. They were really hard to sell. The same with the GP Cars, who really bought a complicated and expensive GP Car, which couldn't win?
Maybe Alfa produced Parts, to assemble 8 Tipo C, but how many actually raced? I believe, only the private SF Cars, recieved a SF Number, not all.