| Business | Phone |
| Whitten & Borges 645 Grand Ave # H, Billings 59101 | (406) 248-5449 |
| Brewer & Assoc 3521 Gabel Rd, Billings 59102 | (406) 256-2077 |
| Structural Engineering Design 115 S 29th St, Billings 59101 | (406) 651-8195 |
| Curry-Riehl & Assoc 730 Main St # 104, Billings 59105 | (406) 256-3699 |
| Phillip C Green Pe 113 White Cir, Billings 59105 | (406) 259-8700 |
| Krivonen Associates 725 Grand Ave, Billings 59101 | (406) 259-1184 |