No, they're not tanks. But I can understand using the term because few people know what an MRAP (Mine Resistant Armor Protected Vehicle) is.
Big question is: Is this report is accurate?
Actually, the refitting of 2,717 MRAPs has been reported before. By left leaning Firedoglake.com, and while the March 2012 press release from the refit contractor said it was a military contract, a DHS adorned MRAP photo accompanied the original story.
There are lots of rumors out there. And there is additional anecdotal evidence that DHS is growing its MRAP fleet. But the specific size isn't clear.
Regardless of numbers, the acquisition of expensive to obtain, expensive to operate, military-style hardware like MRAPs may be among reasons DHS now claims it can't afford to keep illegal aliens detained or the Border Patrol forces intact as the result of sequester budget trimming.