Way back in 1975, my first post college electronics engineering job was working for Ensco, Inc. in Northern Va., designing a track test & analysis system for the FRA. Each system could profile the rails, and one did ultrasonic rail flaw analysis. There were 4 test cars in two sets, labeled T1 thru T4, where T1 & T3 had the instruments and T2&T4 were support cars. One car set was based on Budd stainless steel passenger cars (don't know a model #) and the other set used something out of the Pullman era, I think.
Now the question: Has anyone ever seen these cars in operation? And, better yet does anyone have any pictures of them?