I think your buddy sent you the wrong piece, but I'm a '68 guy.
The basic sending unit on the intake manifold is a one-wire deal for a guage temp reading. I suppose its possible the idiot light was different, but I don't think so. Wiring diagrams I have only show a one-wire connection for the 68.
'68 428 HO M3 Monster, 4-on-the-floor! Need I say more?