that is still available preassembled (hoses and fitting) from GM P/N 25525576, however it lists for 24.16: most parts stores and home depot should have the right size t for about a dollar, and maybe 4-5 dollars for some bulk vacuum line.
If you are talking about the lines from the turbo to the boost solenoid, you are WRONG! The "tee" in that line has a calibrated restriction which makes it work properly. If you replace it with a tee from a hardware store, you will have lost control of boost. Lots of threads discuss that tee, and the size of the orifice. Some were made wrong by GM, and sold as replacements.