170-A is a steelback. 60-A is a leatherback, meaning the top covering material comes all of the way down the back to the beltline. Your pic is pretty small even when enlarged, so hard to tell if the top material is there or not. Rod
It is a steelback, there was never any top material on the back. There is also a strip of moulding around the top on the back that stops the material from going down the back.