I hired out as an onboard service attendant in January, 1987, just before my 41st birthday. Worked OBS on many different trains and different jobs based in D.C. These included the Capitol Ltd. to Chicago, the Palmetto to Savannah, the Montrealer to Montreal, the Night Owl to New York and Boston, and some N.E. Corridor trains. Some of these train schedules have changed significantly since 1987. Later that year I transferred to Auto Train because the jobs on the Montrealer were cut, resulting in a surplus of manpower on D.C.-based regular service.
Onboard Service attendants are covered under the railroad retirement system. However, I had already contributed to Social Security for 25 years when I started working for Amtrak. In June, I retired from Amtrak at the age of 68, with 310 months (almost 26 years) of service. Several months were not counted because of sick leave or being away from the job for various other personal reasons. I don't fully understand the byzantine provisions of railroad retirement. I can tell you for certain that my current retirement income would be far better if I had stayed for the full 30 years (360 months), or if I could get full credit for all those years I contributed to Social Security. But 360 months would mean working for over four more years and retiring at the age of 72, or maybe older. Onboard service can be very physically demanding, largely because of the odd hours, short sleep, rapid turnarounds, irregular meals, and various issues that are just part of the job. I don't think many people over 60 are up to it. It was a real challenge for me over the past few years. In fact, there are a lot of people well under 60 who would have a hard time doing the job. Remember, Onboard Service employees are not considered operating employees because they have no role in actually moving the train. For this reason, they are not covered under the Federal Hours of Service law. Operating employees are guaranteed that their shifts will not exceed 12 hours, and they get federally mandated, guaranteed rest periods. Not so for O.B.S.
This thread has discussed both Assistant Conductor jobs, so I'm not sure what you will want to do. I, myself, was ineligible for an operating job because of imperfect color vision. I'd probably have done better financially if I'd been able to get an operating job. But I think I'll be able to get by OK on this income, and I'm ornery enough to live a long time.
I'm not sure how helpful this information will be, but I hope it helps you to make the right decision for you. Best of luck to you.
Tom