Good fuses Bad gauges

[blazer87]

Hello all, I'm hoping someone can help me. I recently purchased a 87 K5 with a blown engine. I installed a new engine in it and it now runs and drives but i have no gauges working but the speedo. The check engine light and the brake light come on when you first turn the key on then go off like normal and my dash lights work and all of my fuses under the dash are good. Has anyone had this problem or know how i might fix it? Any help would be greatly appreciated.