Mike, everything is correct: L-410UVP E-20 has the MTOW of 6600 kg and has the newer, more powerful M601E; 150 kgph sounds about right for these. M601D is the model used on the old (pre-1985) L-410UVP, which has three-blade props, no wingtip tanks, and MTOW just over 5700 kg (and there is a bulletin to lower the MTOW below 5700 to squeeze it into JAR-23 requirements instead of JAR-25 and not have to install TCAS/GPWS).
Oh yes, by the way - GE has just completed the acquisition of Walter.