the worlord is here

[StainlessSteelCynic]

Personally I think it's a custom built chassis, I can't see it being built on either the M2 or M113 hulls because it's not as wide as either. That would entail some serious bodywork to cut it down from for example the M113 width (3m) to the Black Knight width (2.44m) as well as modifying the drivetrain components to suit the shorter and thinner Black Knight.
From the look of it, the hull is probably stuffed full of the engine, fueltank and drivetrain while the turret is stuffed with the electronics, sensors and weapon with very little space left in either hull or turret.

[cavtroop]

Taking a real close look at the photos - I don't think it's any less wide than a standard 113 - I believe that page to be wrong with the stats. There is little question that's the 113 lower hull.

The drive sprocket is in the front (just like a 113), and the engine access hatch is in the font, too - so it's front-engined. Not sure what the large compartment is in the back. They engine MAY be back there, but with the drive sprockets up front, you'd have a long driveshaft going to the final-drives, and that just isn't a good setup on a combat vehicle. I can't see where the exhaust is, though - nothing in the photos seems to indicate that.

BAE doesn't seem to have any spec's on their page, though, so it may be a chopped up 113 lower hull, but I don't think so. It does say that they're using available technology until other tech becomes available, so this may just be a prototype built on whatever they had laying around.