I normally use Cutler Hammer meter combo load centers, both the wide body 40/40 (MBE4040B200BT) and the narrow 20/40 (MBE2040B200BT). There is an add a lug kit that will fit the 20/40 just fine, so you can put up to a 4/0 on the neutral lug, but it will not fit the 40/40, as the neutral bars are different. My supply house couldn't help me, they said there isn't one available to fit the 40/40. Now the funny thing is, there is a 200 amp breaker available for the 40/40, that only fits the 40/40 since it takes up four spaces, two across. So I can put in a 200 amp subfeed, except for the neutral.
Has anyone run into this, or have a solution? Yes I have an assortment of lugs and I can probably make one to fit, but I don't like doing this, besides there are at least two inspectors I know of that would fail it if they saw it was a "field fabricated" part.