Subaru LEGACY 2002 Quick Reference Index page 171

SPARK PLUG
Ignition
2. Spark Plug
The spark plug's thread diameter is 14 mm (0.551 in) and the gap is controlled to a value between
1.0 and 1.1 mm (0.039 and 0.043 in).
(1)
B2H4152C
(1) Gap : 1.0 – 1.1 mm (0.039 – 0.043 in)
IG-3