It appears to be a close copy of the BAE 4X4 RG-31 Chassis. Which wouldn't surprise me since it is from South Africa. That is where the MRAP originated from and there is several companies that build them down there. They originated from the African Bush War's from the mid-70's.
I'm not surprised you broke that axle, they are way overloaded with the Skeleton and Add-On-Armor boxes. I did ALOT of work on the Caiman and Caiman Plus while I was a contractor in Iraq. The problem is that they are using an LMTV chassis which is crack prone with just an armored cab, hell if you attempt to pick a Caiman up with a HEMMTT wrecker it will snap the frame in half. I got a friend that is a welding engineer for BAE and he was a great asset to me while I was in the field, hell I had everything from engineering schematics to instructions on how to change a tire in an orderly and proficient military manner. I knew more about those trucks than the damn Field Rep's that made 200K a year.
And this didn't replace the Hummer, this did, the MATV...
http://www.oshkoshdefense.com/products/5/m-atv
Oh i didn't break it. I was 63B20H8, i towed it in and put it back on the road. The caiman can be lift towed by a HEMTT, i did it several times. The secret is to rear tow it. The baes were best towed from the rear as well, when you have that option anyway. Max pros and pluses towed fine either way. Cougars tow great from the front, never had a reason to rear tow one. And then there's the buffalo, really not to bad to rig up on either end, they're just damned heavy.