Engine Number, 2.5l

[Dano58]

Hello all..... I'm wondering about the engine in my son's '99 Impreza
2.5 RS. The PO apparently blew the timing belt on the car, and
replaced the original engine with one from an '01 2.5 RS. Is there an
engine number on the block anywhere? It's too cold for me to go out
and take a look.....

And if so, is there a way I can find out how the decode it? I guess I
could call the dealer, but if there is another way to do so, I'd like
to know it.

Thanks,

Dan D
'99 Impreza 2.5 RS
Central NJ USA