C 2500 3/4 Ton Pickup 2WD L6-250 4.1L VIN D 2-bbl (1984)
part number 8635909 (one piston and one seal per package). The oil seal is available separately as service part number 8635568.
Important:
The same design accumulator piston and seal are used in both the 1-2 and 3-4 circuits.
Refer to the appropriate Service Manual for removal and installation procedures.