commandobolt replied to your photo “Two Australian soldiers at Dat Do compound, one wearing an…

commandobolt replied to your photo “Two Australian soldiers at Dat Do compound, one wearing an AN/PRC-77…”

PRC-25

PRC-77 is the upgraded PRC-25 and came into service in 1968.

“The AN/PRC-77 set was an improved version of the PRC-25. Specifications and accessories for the two radios are nearly identical. The only important differences in design were internal; they are virtually impossible to tell apart externally.”

[Source]

Additionally, the source identified it as such, and given that it was a communications unit, I think it’s likely to be identified correctly given they knew what equipment they had used at the time.