The second one looks like a M870A2 (-S ?) 40 ton triple axle trailer…
Most of the specifications for the M870A2S are identical to the M870A2 except for: Updated with Anti-lock Brake System (ABS); Updated with air ride suspension: air springs, shock absorbers, and height control value: and Non-Driving Tapered spindle axle
I may be wrong, but the first one doesn’t look to be in US Army/USMC service to me… 
H.P.