'G' - so based on the very first +8 of '69.
Not sure how the rear lights were configured that early on (on the blue one they're wrong - but probably a lot stronger than fitting the correct style). I'll try to remember to take a look at our handicapper's +8 when he next brings it to Prescott (it's on an 'H' suffix.
Trevmar, thanks for that link - at least it's the right colour and body shape (narrow) to match my '76 4/4.
Cheers,
