The Granada mk3 basically has the same rear arms, but have a thicker casting for the hubs because the run a wider track. The arms you need may well be from a Granada mk3, but I am not sure what you mean with that the arb mounting is on the outer edge of the arm. The mk1 Sierra had it on the outside, the mk2 Sierra and mk3 Granada had it on the inside, next to the brake pipe bracket.