Issue with AWD/front wheel drive/park gear?

I purchased the vehicle listed above. I was aware that the vehicle had a blown head gasket and needed new CV axles. After repairing the engine and replacing the front CV axles, I also swapped out the front brake calipers, pads, and rotors. For the rear brakes, I replaced the shoes, hardware, and wheel cylinders, and performed a brake line flush using Bosch ESI6-32N Brake Fluid.

While replacing the CV axles, I drained the transmission fluid and refilled it with Valvoline Maxlife Multi-Vehicle (ATF) Full Synthetic Automatic Transmission Fluid, Part #773775. When shifting through the gears to properly fill the transmission, I noticed a forward bucking motion from the rear end and heard a grinding noise from the rear differential.

Raising all four wheels off the ground, I observed that the vehicle now seems to roll in park, necessitating the use of wheel chocks to loosen the lug nuts. When in drive, the front wheels aren't spinning, but the rear wheels are, with one spinning faster than the other. Applying brakes results in the same grinding noise from the rear differential.

I pulled and cleared several trouble codes, which may have been triggered by a battery drain during my work on the engine. I also replaced the O2 sensor.

Car Scanner ELM OBD2 Version: 1.99.4/400994/GP DTC report Connection profile: Chevrolet OBD-II / EOBD Date: 7/30/2023 2:59:15 PM VIN: 2CNDL73F656083011 ============================ OBD-IIOBD-II DTCs: 2 P0135 [0x0135] Heated oxygen sensor (HO2S) 1, bank 1, heater control - circuit malfunction Status: Confirmed P0030 [0x0030] Heated oxygen sensor (HO2S) 1, bank 1, heater control - circuit malfunction General Electrical Failures [0x00] Status: GM failure record ============================ Engine control unitEngine control unit DTCs: 2 P0135 [0x0135] Heated oxygen sensor (HO2S) 1, bank 1, heater control - circuit malfunction General Electrical Failures [0x00] Status: DTC supported by calibration, Current DTC, Test not passed since DTC cleared, Test failed since DTC cleared, History DTC, Test not passed since current power up, Warning Indicator Requested P0030 [0x0030] Heated oxygen sensor (HO2S) 1, bank 1, heater control - circuit malfunction General Electrical Failures [0x00] Status: DTC supported by calibration, Test failed since DTC cleared ============================ Transmission control unit #2 No DTC found. ============================ ABS/EBCM/ESCABS/EBCM/ESC DTCs: 1 C0236 [0x4236] TCS RPM signal circuit malfunction General Electrical Failures [0x00] Status: History DTC ============================ EHU (Entertainment Head Unit) No DTC found

I pulled and cleared these codes today (note: I unplugged both front ABS sensor connectors to see if it would affect the rear wheels spinning).

Car Scanner ELM OBD2 Version: 1.99.5/400995/GP DTC report Connection profile: Chevrolet OBD-II / EOBD Date: 8/13/2023 12:27:32 PM VIN: 2CNDL73F656083011 ============================ OBD-II No DTC found. ============================ Engine control unit No DTC found. ============================ Transmission control unit #2 No DTC found. ============================ ABS/EBCM/ESCABS/EBCM/ESC DTCs: 3 C0236 [0x4236] TCS RPM signal circuit malfunction General Electrical Failures [0x00] Status: History DTC C0035 [0x4035] Right Front Wheel Speed Sensor Supply Left wheel speed sensor circuit malfunction; Left Front Wheel Speed Sensor Circuit Low Voltage/Open; Left Front Wheel Speed Sensor Circuit Signal Erratic; Left Front Wheel Speed Sensor Circuit Low Signal Amplitude; Left Front Wheel Speed Sensor Circuit Not Plausible General Electrical Failures [0x00] Status: History DTC C0040 [0x4040] Brake Pedal Switch "A" Right wheel speed sensor circuit malfunction; Right Front Wheel Speed Sensor Circuit Low Voltage/Open; Right Front Wheel Speed Sensor Circuit Signal Erratic; Right Front Wheel Speed Sensor Circuit Low Signal Amplitude; Right Front Wheel Speed Sensor Circuit Not Plausible General Electrical Failures [0x00] Status: History DTC ============================ EHU (Entertainment Head Unit) No DTC found.

I'm uncertain about the next steps. This issue didn't arise prior to my repairs, and I'm concerned I've made the situation worse. I drained the rear differential for inspection, and while the fluid was dark, no metal shavings were present. I have Versatak fluid on order for refilling. I also plan to do the same for the front transfer case. Any assistance in diagnosing this situation would be greatly appreciated.