GMC 1982 Light Duty Truck Service Manual page 350

3C-8 FRONT SUSPENSION
Manually Operating Shock. It should aid the technician to
localize defective shocks caused by internal noise in the
shock, weak, leaking, etc.
1. Inspecting Shocks for Possible Loss of Hydraulic Fluid.
B A L L JO IN T D IAG N O STIC PROCEDURE
Fig. 3C-7--Ball Joint Diagnostic Procedure
(a) Disconnect each shock lower mounting as required and
(b) Inspect shocks for leaks in seal cover area. Shock fluid is
pull down on the shock until it is fully extended.
a very thin hydraulic fluid and has a characteristic odor
and dark brown tint (Figure 3C-8).