I just put a 60amp Powermax Boondocker in my Heartland Elkridge 5th wheel to replace the WFCO stock unit which failed. PM4B-60. Great unit. Randy was a big help! It replaced my 55 amp stock unit.
The powermax is of newer design, so I'd lean that direction. Both are adequate.
Regards, Don My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.