GMC CHEVROLET Silverado 6500HD 2019 Owner's Manual page 398

Service and Maintenance 397
hydraulic system can result in
degradation of power system
performance.
Consult your GM dealer for filling
and bleeding the system.
The power steering fluid filter is
located inside the power steering
reservoir. To remove the filter,
unscrew the large cap on the power
steering reservoir and unscrew the
filter. Reverse the procedure to
install the new filter.