When did???

[livewire]

I know one some clever people on here will know this.

When did Seagull change the villiers carb from a metal float chamber/intake to plastic ones?

The reason i ask, i have a 1972 (FP959H2) Forty Plus which was missing a carb. I have both types of carburettor and would like to ensure i put the right one on for that year.

Thanks in advance,

Andy