GMC 78Z Parts Book – 7817940 NAPA – 277519 – $175.00~ The steering box NAPA # 277519 was used on the 76 to 79 GMC and Chevy P chassis (2 ton truck). The price here at NAPA is $174 with a $160 core charge. The price at Auto Zone is $180 with a $160 core charge.
