Anyway, I was putting together my rifleman dread (standard routine - Aegis Line autocannons, missile launcher and twin-linked lascannon arms) and I cut the lascannon mount too short. You have to cut the lascannon barrels off on the outside of the recuperator section rather than flush with the armour otherwise the autocannon barrels don't stick out the same distance as the ones you fit on the missile luncher arm. Luckily I have plenty of spare dreadnought arms.
That left me with a useless armoured shoulder, and I was about to throw it when I remembered the twin-linked heavy flamer option! The weapons were easy to source (there's a heavy flamer in every dreadnought kit) but it still looked a bit sparse. Then I found the heavy flamer in the sentinel kit, which is quite a bit longer... and Bob's your uncle. A little clipping, a small piece of plastic card, and 'jobs a goodun'
Okay, it's 'triplet-linked' rather than 'twin-linked', but the extra bulk makes it look better. I can't see that I'll ever use it, but at least I have the missing variant in the armoury now.
Comments very welcome...