I was a little too late to see the articulateds run on the IRCA (later FEGUA)...my first trip down there was in late '71. By that time, both were stored at Escuintla, their home for years.
Although they had been given tonnage ratings for the entire system, including the 16 miles of 3.6% of Palin Hill, they mostly ran between Escuintla & Mazatenango.
As far as pics, I do have some in my collection taken by a friend. Maybe when John West gets back from his latest junket, he would be kind enough to scan something.
Malleys or not, that line down there was the most exciting that I have ever been fortunate to ride over. Miles & miles of 3 plus per cent, huge steel bridges, tunnels, fast running and very friendly crews.