That's quite a nasty problem to find - thanks for alerting me! Are there any particular brands of bearing to avoid?

Thanks James - I appreciate your taking the time to read and reply. I'll be shopping for a mainshaft nut tool then....

I've owned an ex military 1984 series III 109 for about a year now, and I have a problem with the transfer box. With the handbrake drum and rear prop shaft removed I found the rear output flange very lumpy to turn, and I imagine the taper roller bearings supporting the rear output shaft have...