Following on from the thread I deleted the main questions in that were based on the original Rod Shift Gearbox (22G1832) and how they differed to the DAM3220 and also if the DAM4818 was suitable for a Moke.
The Gear Ratios and in fact for the most part, the Gears between these Boxes were the same. While the Laygears in the DAM3220 and 4818 were the same and on later '3 Step' Layshafts, the Gear Profiles and tooth Counts were the same as fitted to the 22G1832.
The DAM3220 was fitted with A+ type Main Shaft and Laygear and retained the small Idler Gear in common with the 22G1832, however, the center web on these cases was weaker than the 22G1832.
The DAM4818 was the same as the DAM3220 except that the Idler Gear fitted was the A+ type, the first gearbox to do so, however the center web on these Gearbox seems weaker again than the 3220 series.
In regards to which gearbox of these would be best in a Big Wheel Moke, while they'll all fit and work (and at various times, were factory fitted), I'd have to say none are brilliant, though I'd suggest the 22G1832 would be the pick here.
Big Wheel Mokes are very hard on the Center Web on the Gearbox Cases and indeed the Final Drive, much harder than most Minis. This is all due to the fitting of the Big Wheels. The rolling diameter on a Mini wheel in in the ball park of 20 inches (500 mm) where as on a Big Wheel Moke, it is 24 inches (600 mm). In order to get an acceptable Final Dive Ratio and maintain the 'magic' 16 mph / 1000 RPM mark, it was necessary to fit a short Final Drive of 4.2:1, however, this also increased the torque mulitpication considerably at the Final Drive and also on the Mainshaft Bearing, that's located in the Center Web. Added to this is less than ideal (actual) Gear Sizing and things start to stack up.
On top of this added torque multipication at the final drive is a further multiplcation of torque added by the increase in wheel diameter.
These factors are not only on 'drive' but also on 'over-run'.
Overall, even before anything is done to increase power outputs or make the tyres more sticky, in totally standard form, the Center Web in the Gearbox and every other part of the drivetrain there after, 'see' an increase in torque of 50%.
For these reasons, when given a choice, the only gearbox case to use in a Big Wheel Moke is the DAM5626, which was developed for the MG Metro Turbo and then became standard across the range.