It's a chassis/engine/drive train for Blackwater's Grizzly APC...
Starting with the "Seagrave" tag in the ebay pics, I Google searched "did Seagrave make mrap in 2007?" and found the Seagrave Fire Apparatus Company website. Site says they make MRAP. See italics below. :ylsmoke::
https://www.seagrave.com/government/company-capabilities
DOD Agencies – Tactical Trucks, Truck Chassis , Missile Transporter, Mine-Resistant-Ambush-Protected (MRAP) Trucks, Aircraft-Rescue-Fire-Fighting (ARFF) (Military Tactical Vehicles), Spare Parts Support
But there were no pics on the Seagrave site. Back to Google. Found a reference to Seagrave making APC named "Grizzly". Pic showing split windshield and single rear wheels indicate this chassis isn't the ebay one. Italics is excerpt from link.
https://en.wikipedia.org/wiki/Grizzly_APC
The first Grizzly was built on a commercial GMC chassis. The current versions are built on a custom chassis supplied by Seagrave Fire Apparatus, Clintonville, Wisconsin.
Then I found it. The Blackwater Grizzly APC! ( :clapsmile ) Vehicle was Blackwater's (the now defunct security business) entry into the military's JLTV (Joint Light Tactical Vehicle). Pics show single and dual rear wheel vehicles, both with single driver seat up front (no passenger seat). Italics is excerpt from link:
http://defense-update.com/products/g/grizzly_bw.htm
The vehicle's diamond hull shell is attached to a Seagraye chassis, powered by a 330 hp caterpillar C7/3126E turbo-diesel engine.
In November 2008 Defensetech.org announced Blackwater was ending it's Grizzly production. Article refers to these JLTV's as "MRAP II". The MRAP II is essentially a lightweight MRAP. Italics is, well, you know....
http://www.defensetech.org/2008/11/24/blackwater-shuts-down-vehicle-manufacturing-updated/
Blackwater USA, the private security and training company, has shut down a large part of its manufacturing subdivision after losing the Joint Light Tactical Vehicle program and facing dwindling demand for its “Grizzly” Mine Resistant Ambush Protected Vehicle.