A friend of mine has a 396 in his 55 Chevy and we were wondering what it originally came out of. The numbers on the front pad go like this
T0716LB S280425 The 6 in the first number could be a b.
If someone could point me to where I could find it out or help by decipering it that would be really cool. Thanks Man, Mac

Mac,
Here is a link to a sight that has all the info you want.
http://www.nastyz28.com/chevy-engine-code-stampings.php

Thank you for the link BillK, we appreciate it.

I'm getting it was built at the Towanda plant and it's a 65 Chevy 325HP 396 that was hooked to a powerglide.

LB code was used twice :
LB 65 396 Impala 325 L-35 Power Glide 4-Brl Holley
LB 69 427 Impala 335 LS-1 3 Spd 4-Brl

So you might want to check the casting date.