There's one of McKinnon G-21G Turbo Goose s/n 1205 when it was ZK-ERX in Tuvalu between 1980 and 1984:

Of course, technically speaking, the caption on the stamp is incorrect in that after its conversion and re-certification under TC 4A24 in 1969, it was no longer a "Grumman" at all.
And while I was looking for a copy of it online, I also found these:

Is that enough to get this thread off and running?