C0036 & C0037 are DTC's for the left rear wheel sensor. 97 Astro has only one sensor for the rear wheels and it doubles at the VSS (Vehicle Speed Sensor) and neither DTC applies to your vehicle.
C0065 & C0066 are not used, (reserved for future ABS systems).
C0073 & C0086 are computations that the EBCM makes to determine the duty cycle it applies to the solenoids.
I would look for a poor ground, a poor power connection, or possibly a faulty EBCM.