Fitted mine too, thanks for posting pics steve, and for all the other folks who've discussed the ins and outs, making it a bit easier to sort out...
Cutting a huge hole in a tank worth a couple of hundred squids is NOT a natural thing to do, I was racked with nerves doing it, but it seems to be water-tight, and within a couple of hours I had toasty very-warm water... Actually looking forward to Monday now!