I can probably help you on this as I've owned most of these buggies since the 808 through XB8 / XB9 and finally the current XB8E.

The center diff's hole spacing is identical from 2008 to 2018 inclusive, and the center driveshaft lengths are the same too.
This applies to all the nitro buggies within that period, and all the E versions from XB9E onwards.

The 808E you mention is unfortunately the strange exception (to the above) in the lineup, as it uses different length driveshafts (longer in front) and mounts the center diff further back.
It also uses wider hole spacing for the motor mount, subsequent versions (including current) use identical chassis hole spacing for the motor mount and front center diff mount.
To use the updated/modern motor mounting location you'd need to change the chassis, F/R driveshafts, modify the radio box location, and find a solution for the motor mount.

Feel free to get in touch if you have more questions. I may also have some parts if needed, likely the chassis and driveshafts.