Good for you
Non-upholstered seats can now only be found in suburban commuter trains. All LD train accommodation has some level of upholstery. Even the lowliest non-airconditioned Sleepers have upholstered berths. Officially there is no third class anymore, though there is an accommodation referred to as 3AC (or T on the side of the coach), which denotes 3 Tier AC Sleeping accommodation.
Recently they have introduced a higher density version of 3AC which is denoted by "G" outside the carriage which carries the sardine stuffing to the extreme by hanging a middle berth between the upper and the lower berth on the corridor side of what otherwise would be a 3AC, and this provides probably the cheapest ariconditioned sleeping accommodation anywhere in the world.
BTW, I will be in India between the 16th of Dec and 2nd Jan. I will be traveling New Delhi to Howrah by 2302 Rajdhani by 1AC.