Over the years many changes have taken place in the turbo industry. Where there were once many smaller manufacturers, mergers and buyouts have left only a few large major manufactures. Some of the old names have remained active while others have been fazed out, but either way most of the turbochargers available today are made by either Borg Warner or Honeywell. Both are top quality manufacturers who are now the original manufacturers of replacement turbochargers for most engines. Below you can see a history of the industry:

Schwitzer, KKK, BorgWarner, Holset
1918 Schwitzer Company Founded in Indianapolis/USA
1962 Schwitzer collaborates with AG Kühnle, Kopp & Kausch (Germany) and Holset (U.K.)
1973 Holset ownership changes twice, first is was purchased by the Hanson Trust and then by Cummins Engine Company Inc. 1998 3K-Warner Turbosystems GmbHis founded as a BorgWarner subsidiary after Borg Warner acquires the supercharging systems division of AG Kühnle, Kopp & Kausch
1999 BorgWarner takes over Schwitzer and integrates it into BorgWarner Turbo Systems along with 3K-Warner
2003 3K-Warner Turbosystems GmbH is now called BorgWarner Turbo Systems GmbH

Garrett, Honeywell, AiResearch, AlliedSignal
1936 - Cliff Garrett formed Garrett Turbochargers.
1950’s - AiResearch Industrial Division is formed.
1963 - AiResearch merges with Signal Oil and Gas Company.
1980’s - Allied Corporation and the Signal Companies merge into a single entity, Allied-Signal, Inc.
1999 - Allied-Signal merges to becomes part of Honeywell.
2004 - Formally change their name to Honeywell Turbo Technologies, while Garrett® has been retained as a product brand name for aftermarket.

Roto-Master, Rotomaster
Roto-Master was purchased by Garrett and done away with. Rotomaster was reportedly formed when they purchased much of the Roto-Master tooling and began production again.