- Vanguard Short-Term Government Bond Index Fund and ETF (VSBSX/VGSH)
- Vanguard Intermediate-Term Government Bond Index Fund and ETF (VSIGX/VGIT)
- Vanguard Long-Term Government Bond Index Fund and ETF (VLGSX/VGLT)
This means the Vanguard Long-Term Treasury Index Fund (VGLT) is a bit more suitable for the bond component of the Permanent Portfolio and related strategies.
If you're switching from long-term to intermediate-term U.S. Treasury bonds, the Vanguard Intermediate-Term Treasury Index Fund (VGIT) is also an option.
The three funds have a decent cost advantage: the expense ratio is 0.07%.