David, I seem to have led you astray a little. The 1800s were the last of the Red Rattlers, by 1960 they would have been on borrowed time, these were AECs, photo below.
The 1900s were Stainless with blue trim, some lacked the blue on the sides. These were introduced in the mid 50s. They were also AECs, but had problems with the gearbox. Photo below.
From 1959 the 2000 class superseded the 1900s. These were also AECs, fitted with SCG of Coventry four speed gearboxes. Photo below.
Your railcar must’ve been an 1800, as all other Red Rattlers would’ve been retired by 1960. Details of each individual unit would have varied as they were modified to fill their differing roles.
I fully empathise with your hazy recollections, who are you? 