[oletrucks] can someone ID this block?

[Jeff_Wilson@unctv.org (Jeff Wilson)]

Hi all... I've got a 283 engine- I know it's a '66, but
that's about all I know.  Weren't there some 283
blocks that had thicker castings that could be
bored out to 4"?  I'd be delighted if this was one of
those....  Can someone check this casting # and
tell me what I've got?
Casting # is: 3834810

Thanks greatly to whomever!

CJ Wilson
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959