The information below came from a table on the Japan site. If we have someone that can interpete the language, there is a lot more information. The link to the actual table is here.
TH-58PX600 *** TH-50PX600 *** TH-42PX600 *** TH-37PX600
145.4×91.8×9.9 cm *** 126.6×80.2×9.5 cm *** 107.7×68.9×9.5 cm ***97.7×62.9×9.5
62.0 kg *** 44.0 kg *** 33.0 kg *** 29.0 kg
W 455 *** W 345 *** W 285 *** W
498 kWh *** 418 kWh *** 309 kWh *** 239 kWh
1,366×768 *** 1,366×768 *** 1,024×768 *** 1,024×720
One thing that bothers me: The TH-58PX600 AND TH-50PX600 have the same resolution (1,366x768). Does this mean that the 58 has larger plasma cells that could cause some SDE if viewing from less than 8 feet