I assume you're talking about the Lexus RX model range. While there was an RX 300 (when the RX had a 3.0 L engine), the hybrid version was the RX 400h or RX 450h (depending on year).
The RX hybrid AWD system is the one from the Toyota Highlander Hybrid; a similar system has since been used in every Toyota/Lexus hybrid model with a transverse engine and AWD.
The rear drive unit is essentially the same as any other drive unit of transversely mounted motor and fixed-ratio transaxle. The motor within it is probably identical to the output-side motor within the hybrid transaxle (MG2), and is sometimes called MGR.
There was extensive discussion of this unit for EV conversion in this forum a couple of years ago. The biggest issue with it might be the lack of cooling: it is only used in the original application for brief periods when extra traction is needed, and will get too hot is used continually at any significant power.
The battery size does not indicate the time for which the rear drive unit can be used, because the hybrid transaxle in the front can supply the required power indefinitely. Electric-only driving (which is very limited in duration and power in any non-plug-in hybrid) would normally be done with the hybrid transaxle at the front rather than the rear drive unit.
The RX hybrid AWD system is the one from the Toyota Highlander Hybrid; a similar system has since been used in every Toyota/Lexus hybrid model with a transverse engine and AWD.
The rear drive unit is essentially the same as any other drive unit of transversely mounted motor and fixed-ratio transaxle. The motor within it is probably identical to the output-side motor within the hybrid transaxle (MG2), and is sometimes called MGR.
There was extensive discussion of this unit for EV conversion in this forum a couple of years ago. The biggest issue with it might be the lack of cooling: it is only used in the original application for brief periods when extra traction is needed, and will get too hot is used continually at any significant power.
The battery size does not indicate the time for which the rear drive unit can be used, because the hybrid transaxle in the front can supply the required power indefinitely. Electric-only driving (which is very limited in duration and power in any non-plug-in hybrid) would normally be done with the hybrid transaxle at the front rather than the rear drive unit.