What does E71 mean on a casting?

[Jay Whitely]

Hey guys,

On an S13 Silvia SR20DET motor, all the intake valves
have 53J stamped on them. The machine shop that did my
valve job replace one of the intake valves because it
was bent. The valve they put in there is the same
size, but it has E71 stamped onto it. What car is this
from?

Thanks,

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Jay Whitely
Tampa, FL
1996 200SX SE-R
GTi-R powered, F-MAX Stage 2