New DD, need engine ID help

[~Whitey~]

Hey all, I got a great deal on this 86 Silverado K10 Short that I just couldn't pass up. Emissions sticker by radiator says 5.0 (but thinking it's been changed out since 86). The block casting, engine ID have me confused and wondered if you guys could help me identify what motor is in this truck. Transfer case is 208, tanny is th400

3970010 - BLOCK Casting #
V1003TBF ? - Engine ID (see pic)
C9S118814 - Engine Serial (see pic)




I can't tell if the first letter of the Engine Suffix is I or T ?

As I understand it
V = Flint
1003 = October 03, thought the zeros are different shapes
TBF or IBF ?? engine suffix
C9S118814 - Engine Serial, I don't know how to read this for any info.

Thought with all the info one of you guys would know exactly what motor this is.

Thanks in advance