Help Identify this engine!!

[SDT16]

Ok. I found some more #'s.
On the top of the Bell housing is " K1931"
On the Heads:
Right: C81T-6049
Left: C81T-6050

Top of Block left Hand Rear: R381049P in a Slanted Font

link to pix:
http://gallery.me.com/sderen#100051&...or=black&sel=4

Thanks for everyones help.

SD