[Kenth]

I guess the 17056261 never got into production since it can´t be found in the Delco Parts&Service #9 manuals.

1976-78 Pontiac M/T Qjets has .038" idle tubes and .110" idle bypass air in the throttle plate add to that about .092" from the hot air choke channel, were the A/T units got no other idle bypass air than .092" from the hot air choke channel and .031"-.035" idle tubes depending on year and application.
Depending on vacuum control system used some got a ported source and others not.