Theramax/Therflo Pumps, 48 Frame 2.5/4.2 HP used in Sundance spas (06/2009+ ) Specific pump part numbers (Emerson/US Motors) pump/motors: 6500-341, 6500-343, 500-345, 6500-347, 6500-349, 6500-351, 6500-355. Used on Emerson 56 Frame 6500-352, 6500-363.