Tri-Power

welcome to the heard.
Alot of information can be found on ultimategto.com for example the answer to your question:

1966 GTO Specifications - UltimateGTO.com

Length (in) Width (in) Height (in) Wheelbase (in) TrackF (in) TrackR (in)
206.1______ 74.4______ 53.2_______115.0_______ 58.0 ______ 59.0

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1966 GTO bored 389 Tri-Power, Powerglide(#'s Match)

{GTO, Explorer, Galaxie, Glastron, & Yamaha} -Tyler-