They were bare bones but did the job. My one trip in one of the NYC slumbercoaches was unremarkable and wasn’t aware of much difference from a roomette (thinner mattress -like Amtrak, linoleum floors).A Heritage 24-8 slumbercoach had capacity for 40.
A Heritage 16-10 slumbercoach had capacity for 36.
No doubt the design plans Bombardier - now Alstom- acquired from Budd in 1987 are still in their archives. But Amtrak insists on reinventing the wheel.