I have "Integral Cases". The parts fisch shows these were originally on K100RT models.
45 54 2 316 357 (L) & 45 54 2 316 358 (R).
My problem is that my new Full Face helmets won't quite fit inside them....the lids lack about 1 1/2" from closing.
I've seen that BMW sells extended lids for cases similar to these, but because I don't understand all the official descriptions on the parts I'm not sure they will fit.

Please share your knowledge on this.

Also, I've considered heating the side of the lids I have and "stretching" a bubble in them for extra clearance for the helmets. Anyone tried this?

Mk. 3 versions did have wider lids, and would probably fit on a mk. 1/2 base.

But mk. 1/2 have the gasket in the base, and mk. 3 in the lid......
don`t know how good that will match....regarding to being waterproof.

Have a look at this.

Most work would be latches, as they are turned 180^o on the mk. 3 versions....
so you have to drill new holes.

If you still find this interesting, I`ve earlier posted the the difference between
the holes on mk.1 and mk.2/3 latches to Rick G........you have to search.

Just had this problem with my mk3 panniers and a new helmet.

Wound up with the helmet upside-down, facing backwards and angled about 15deg away from me

It did go in though.