The layshaft isn't lower, the bulkheads are cut shorter.

Second point

So do you think the original centre wt will now fit,or a new one for the 17

But if the bulkhead is shorter. not going to extend any Crown below the chassis?

By bulkheads I'm pretty sure he meant layshaft/motor mount holders.

The top of the layshaft holders have been reduced in size. So when the top deck mounts directly to the front and aft bulkheads, there is still a 1mm gap between the layshaft holders and the top deck.
So if you want to run the layshaft screws with the new car, you will need to add 1mm shims as well.

Not sure on this, as there are holes in the brace to connect top and bottom, which would go exactly where the centre weight currently mounts...

I've been told it does not fit, but that's 3rd party info...

If the layshaft does not sit lower, the bearing would still touch the top deck. That's probably why they keep shimming it. But it seems strange to solve it this way. Anyway, I have to take a better look next time :-)

HK Today release T4'17 kit

The-Border.com ships the XRAY T4 2017 today.
Here are the first pictures:

Looks like the floating steering comes standard now.

the bulkhead seem more under part top

Your incorrect there, as the bearing is captive, and not close to the top deck even as it is in the 16. The layshft has not been lowered, just material removed from the the top of the holders.

Carbon top plate does as it's a new part... due to the servo now being mounted on the centreline. If you used the old version, it would have the mounting points off to one side. And then there is the lugs on the alloy part as well....