Help Identifying Iranian Army uniform and gear circa 1970s/80s

Hello,

I want to know what style of uniform these troops are wearing, whether it has western origin or is an indigenous design. Would be great if boots and pouches can be IDed too.

Circa late 1970s:


From this famous picture I want to ID the gas mask and strap/harness.



Or this gasmask:



Harness and pouch in these pictures:

1st Gas mask looks similar to a US M17 and all I can make out of the webbing is a DDR Strichtarn Ak mag pouch.

Aside from the East German magazine pouches, the rest of the webbing looks like the same as the IDF - certainly the suspenders and belts are identical, and probably the ammunition pouches as well. Notice the strap and buckle assembly that is fitted to the centre rear of the belt - it also appears in the Iranian photos.