Item 15131 Rev-Tuned Motor (Single-Shaft, 1992)

SEALED REV -TUNED MOTOR - ITEM 15131 (DISCONTINUED PART) Single-Shaft 1992 Vintage / Classic Parts
“As its name implies, it is a speed-focused motor and has higher power but lower torque when compare to Torque-Tuned Motor.
The original version of the Rev-Tuned Motor has the Mini-F label as it was originally a upgrade parts for Mini-F. The second version changed the label to replace the word 'Mini-F' with '4WD' (as in Mini 4WD). [This is the motor for sale, in the photo]
The original Rev-Tuned Motor had the purple endbell cap, while the rest of the Rev-Tuned Motors have the blue endbell cap. 
Due to its lower torque, it is not recommended to use on Mini 4WD cars with large-diameter wheels and low-gear ratios.” (https://mini-4wd.fandom.com/wiki/Rev-Tuned_Motor)
Spare parts are 100% Tamiya, from my personal collection.