Plymouth Tambour Westminster Chime with 124 Movement

I am familiar with Seth Thomas' Plymouth Clocks as they were less expensive alternatives to Seth Thomas clocks in the 1930's, but this one totally stumps me as the cabinet is above the usual standards for Plymouth and it uses the Seth Thomas 124 Westminster movement with 5 chime rods vs. the usual 4 I see in other Plymouth models using the same 124 ST works. Can anybody shed some light on this clock? Any information on Plymouths using 124 ST's vs. the 4000 series and 89 series would be most welcomed!

Dan