Fuel Gauge regulator question

Yeah I know I read a million gazillion posts on it also. :)

It's a 72.

Was confused about the pulsing voltage thing... Must be the gauge itself....I sawpped in a known good regulator from another car and still same issue- the grounding thing still doesnt work. So I just swapped in the whole cluster from my other (project) car...and it's working now.

Will check out your ebay advice- thanks!