[Greg Reid]

I definitely prefer the GTO tail lights in a '68...but that's just me. 8^)
Dual snorkel breather is a '69 feature. The '68 just had a chrome lid on a single snorkel.
Chrome valve covers.
Rocker moldings had no engine callouts.
Fenders had the "GTO 6.5 Litre" badges
No Pontiac or Lemans badges on trunklid. Just a metal GTO on right side of lid.
Chrome bumper can stay but it has different headlight buckets than the Lemans, if I recall correctly.
GTO on driver's side grille, inboard of the headlights.
Lower valence is the same for either.
Woodgrain dash inserts on the GTO.
"GTO 6.5 Litre" badges on inside door panels.
Some GTOs came with bench seats and column shifts...but if you're cloning one, you just gotta go with a Hurst Dual Gate and console with buckets.

By the way, the easiest way to recognize a TH-400 for me is that the pan shapes somewhat like the state of Texas.