Subaru Legacy 2003 Service Manual page 1723

MECHANICAL
16) Installing piston pin:
(1) Apply a coat of engine oil to ST3, and then
insert the ST3 into service hole to align piston
pin hole with connecting rod small end.
ST3 499017100 PISTON PIN GUIDE
ST1
(2) Apply a coat of engine oil to the piston pin
and insert piston pin into piston and connecting
rod through service hole.
(3) Using the ST, install the circlip.
ST 499897200 PISTON CIRCLIP PLIERS
NOTE:
Use new circlips.
(4) Apply fluid packing around the service hole
plug.
Fluid packing:
Part No. 004403007
THREE BOND 1215 or equivalent
(5) Install the service hole plug and gasket.
CYLINDER BLOCK
ST3
ME-00158
ME-00159
ME-00160
ME(H4DOSTC)-78
NOTE:
Use a new gasket.
ME-00140