I got mine today and have been playing with it a bit. The good news is that the new bulkheads will fit all older models no problem. The single speed tranny is in the exact same case as the X, so it will bolt right in too.
The diff ring and pinion are new and look tough as nails. The bearing on the ring side is now larger so it should hold up better.
The trans has a new primary gear and a new thicker idler shaft. Hopefully it will hold up well.
The motor mount is massive! Should clamp great.
I put on the optional 25 tooth pinion and will run it with two 3S 5000 Flightpowers. I also put on some stiffer springs on the big bore shocks. It comes with the pink spring (medium-soft). I used the white springs (medium-stiff).

Got any pics of the Flux?

Also would be nice to get some "real" measurements of the battery compartment.

I'll put some up tomorrow night. Is there anything special you would like to see?

A few more details, the battery boxes are nice! The accessories bag has foam blocks and foam strips to customize the internal size. Box size is 30.4mm x 51.1mm x 201mm. (Rough measurement with calipers).
The outdrive dogbones are the new XL large head style. The front and rear bones are the same smaller size as the X.
The ESC mount is held up by the frame on one side and a thick hollow plastic standoff on the other (next to the motor).
The radio box has a lot of room with no throttle/brake servo or reverse servo. I took out the AM RX and put in a Futaba 2.4GHz system.
The center of gravity is impressive. The motor sits low and the balance is much better than the standard nitro X.
Of course, the real test will be how it holds up after numerous backflips and wheelies! HeHeHeH.

Thanks for the info. Now I can order some 3s packs. I'm interested to see how it drives for you.

Were you able to get an idea if the diffs need shimming out of the box?

I gotta get my battery situation figured out soon. I have two 3S packs right now, and need to order another set. I just dont know if this thing will run on 4S, or if I should just stay at 6S? I dont really want to mess with having a 2Sx3S system...like to keep even numbers!

Somebody has got to post detailed batt tray pix. This is killing me lol
Take some tranny pix too!!

How much to the door btw? Does this qual for HPI's rebates going on now ($50)?

i was wondering about the rebate also but I don't see the flux listed. If you're a towerhobbies saver member though you can get $60 off until 1/31 with code they email you.

Some pictures.

More pics.

Even more.

there no grease in the tranny????

How is the ESC on/off switch attached to the ESC?

Nice truck!!!

Will the Flux tranny fit in a Savage 25? Thanks

The diffs are already shimmed out of the box. Each side has 2 0.2mm shims. The pinion has 1 0.2mm shim. Very little play.

Nope, no grease in the tranny.

The switch is mounted to the ESC plate. It is completely sealed with a flexible hood. It's the white square in the last picture behind the three motor leads.

Weight is 11 pounds 6 ounces. I already bought an extra bulkhead and R&P set just in case. The HPI website has them in stock.