Brake Booster line?

[70Delta]

I have a 2000 Tahoe and would like to do the Seafoam treatment. I can't seem to find the brake booster line. If someone could help me identify which line to feed the Seafoam into that would be great.
Thanks

 

[JennaBear]

Look for the line that goes into the vacuum booster (big metal drum).

 

[70Delta]

Thanks for the help.