Vietnam era US equipment
 

I came across this ex-US military Vietnam era equipment last summer and was wondering if anyone could supply a little info. The first one is a Seaman Gunnison US Marine thing that must have been for transporting boats. The next is a 56 GMC 3 ton 4x4 US Army truck. The last is some kind of all terrain transport vehicle. It has 4 axles with 4 wheels each and is articulated for steering.

Here's the 56 GMC.

Here's the last picture. It had polar something written on the front.