I have a K-301 A,spec no.47138B,the tractor a 125 with serial 271,612 which makes it mfg. in Nov.1968.My friend is going thru the engine.I asked him to check the balance gears.I've heard good and bad about them.He stated no gears,in fact the block wasn't even threaded for installation. When did these gears 1st start being installed?Or has my engine or i.d. plate been switched?Appreciate the help guys.