Seperator plates, Transgo vs stock

So I managed to trace out the circuit this morning, and it's a restrictor between the 1-2 shift control valve and the accumulator. First one of these I had came with an O/D HD2 kit, but I've bought a few more since, to replace checkball damaged stock ones. I guess I need to call Transgo and get some info on the how's and why's, especially as the shift kit's references to the plates are kinda confusing.