12 tooth gear 16 pitch 20 degree pressure angle heat treated with 3/8-24 right hand threads.  These are very hard.  RC62.

Do not pry. Use a 12 point 13/16” socket to turn the gear. Hold the clutch drum with a band wrench. We also have a snap ring inbetween the two bearings, so you must tap the lower bearing out once you have removed the clutch drum and shaft.  Use a 1/4", 5/16" bolt or punch and tap out the lower bearing that wold be closest to the engine.  Once that bearing is removed you can press the upper bearing out and remove the Int. sna ring. 

78 mm Clutch Drum / Oil Filter Band Wrench with Swivel handle.

Note: We have never, since 1984 had to replace one of these 12 tooth gears and most all the gearboxes that we have sold are still working.


Below is the clutch drum that uses these gear.

Clutch Drum 78 mm with a 5/8" shaft & 3/8-24 threads

http://www.staton-inc.com/store/products/Clutch_Drum_78_mm_with_a_5_8_shaft_3_8_24_threads-866-0.html