In the 1970s, the US Army wore two basic types of field uniforms.
Primarily the OG 507 fatigues were worn. These were olive green, shade 507, poly-cotton or all-cotton blend shirt and trousers. The all-cotton versions were being phased out in the 70s. This uniform consisted of a long-sleeve shirt tucked into the trousers.
The second uniform, although not universally worn were the jungle fatigues, an all cotton ripstop material, with a bush-style shirt worn untucked.
Some units, such as the Rangers and Special Forces wore a camouflaged version of the jungle fatigues. The pattern was slightly different from what became the 3-color woodland pattern, with a lighter fourth color.
The ballistic vests (commonly known as flak jackets) were essentially what was worn during the Vietnam War, with minor updates to the vest rigging and comfort. These began to be phased out with the introduction of kevlar vests in the mid-80s.
The woodland pattern BDU was phased in in the early 80s.
The M60A1, A2, and A3 MBTs were all used in the 70s, with all A1 and A2 models being upgraded to A3 status towards the end of the decade.