An interesting post from my archive of interesting posts:
Subject: Re: 3TTT Stem/Bar question [classicrendezvous] Date: Thu, 10 Aug 2000 From: Aldo Ross
(I shall try to list some of the history of TTT stems, although there will be large gaps, which I hope other list members can fill...)
TTT stems were originally known as Ambrosio, which also made bars and rims, both in aluminum and steel. The Ambrosio "Champion" family goes back to at least 1953 (page 190 "World of Rebour"). The "Champion" was available in polished aluminum or chromed steel, and was still being sold as late as 1964 (Reliable Cycle catalog, 1964, page 42) Also available was the Ambrosio "Super Corsa" adjustable alu stem. The "Champion" came in 8, 9, 10, 11, and 12cm lengths. These stems were stamped "AMBROSIO CHAMPION" on top of the bulge where the bar passed through.
By 1963 Ambrosio had introduced the "Gran Prix" stem, which updated the "Champion" by eliminating the point at the rear, behind the edge bolt head (Evian Cycles catalog, 1963, page 43). This was soon updated again, to a recessed allen-key wedge bolt. Some of these stems included the text "MADE IN JTALY" (sic) on the right side, and "GRAN PRIX" on the left.
There was also a lighter version of the late Ambrosio stem, with wedge cuts running side-to-side on the base rather than front to back, and an I-beam section to the extension. This stem said "MADE IN ITALY" on the right, and "AMBROSIO SpA" on the left.
Sometime between 1964 and 1973 Ambrosio became TTT (Bike World Magazine, October 1973, page 18). In 1973, TTT still made the old Ambrosio adjustable, the Gran Prix with allen-head wedge bolt, and the "Record", which was lighter than the Gran Prix by 1 ounce! The Record had the extension length cast into the stem, and was available in 6.5, 8.5, 10.5, 11.5, and 12.5 mm lengths. By 1979 the Record stem has an allen-head bar clamp bolt, and came in sizes 60mm to 140mm in 5mm increments (International Pro Bike Shop catalog, 1979). The Record was the first to be anodized...the others in the family had all been polished bare aluminum.
Wholesale for an Ambrosio "Champion" stem in 1964 was $2.65. By 1980 the retail price for a TTT "Record" stem had soared to $16.95!
Anyone with other information please feel free to fill in the gaps.