The trans ams built in the late used two engine choices an Oldsmobile 403 and Pontiac 400 it is your understanding that only way to get was also 4 speed?

That's not quite accurate. While the Pontiac Firebird Trans Am in the late 1970s (generally considered 1977-1981 for this discussion) *did* offer the Oldsmobile 403 cubic inch V8 and the Pontiac 400 cubic inch V8 as engine options, a 4-speed manual transmission wasn't the *only* way to get either engine. Automatic transmissions (typically three-speed automatics) were also available with both engine choices.