In Reply No. 3 I mentioned a book called The Kennedy Detail, by one of the agents. I found it and went through it again. The book actually took shape at reunions of retired agents and many actively participated, finding old records and sharing recollections. A few men felt honor bound not to get involved, but many who did said it helped them find cloture for something which had haunted them for the rest of their lives. Of course, they may have had personal or institutional reasons to dress up the story, but with so many people involved, the main thrust is probably pretty accurate.
Ike addressed the men as "Agent", much as he might call someone "Lieutenant", and he kept the relationship professional. JFK learned and used first names and often made small talk and involved the men in the life of the family. Agents were put in sweatshirts and drafted on to touch football teams, Kennedy personally carried an armload of short sleeved shirts out to men sweating in suits under the Florida sun and gave an extra scarf to another shivering in a Washington snowstorm. Once in Florida Kennedy was doing a little sailing. He docked the small boat and asked four agents if they would like to take it out for a spin. They knew nothing about sailing but he told them it was easy and they would get the hang of it. Naturally, it immediately tipped over, hopefully in shallow water. Kennedy roared with laughter and after just a moment, so did they. Agents loved Hyannis Port, since the compound had been designed for security, but Florida made them nervous, as the property backed to a public beach and open water. JFK's Lincoln was built by Ford with no input from the Secret Service. There was nothing bulletproof about it. It was rated at 300hp but weighed almost 4 tons so probably not too peppy. Jerry doesn't mention it but I bet the suspension was tuned "soft", not "high performance".
One of Jerry's war stories bears repeating. After Dallas everyone flew back to Washington and Jerry found himself covering the back of Johnson's house, where he would spend the next few nights. Everyone had been issued Thompsons. They used a technique where traffic around the perimeter went one way, so an intruder ran a 50% chance of coming in the wrong way. Double shifts were worked during presidential travel and Jerry was about half way through his second consecutive eight hour shift. He was fighting sleep and trying not to get spooked by the shadows when he heard someone approaching from the wrong direction. He raised his weapon (doesn't mention the safety) and when the form materialized, it was Johnson. Jerry said LBJ turned white as a sheet when he comprehended the situation. Think what people would be saying today if the ball had taken a bad hop on that one.
Meant to say, Jackie called the men "Mr. (last name)", was very devoted to her team and requested them for her New York period.