I am not a mechanical engineer but I love the topic and try to learn as much as I can. I have thought about reducing the usual differential ring and pinion gear diameter to increase ground clearance (and other reasons too lengthy to explain here). I also want to keep the shaft speed as high as possible to reduce torque and keep the parts smaller. I plan to use a portal axle but I want to go further. I am thinking of a differential that is nothing more than a spool/coupling with a gear that has teeth on the outer diameter. I think this might be reduced to 3 inches in diameter with proper care and design principles. The differentiation, will be done in the portals. I will probably use an input shaft that is 2" in diameter due to high power (800-1200 H.P. or more) and loads and also it will be a through shaft to power multiple axles. I have thought of a few ideas, but I think there might be better ways to do it. I have thought of using a jackshaft driven by the input shaft that has a worm gear in its center. I have thought of bevel gears (or ring and pinion gears) on a shaft 90 degrees to the input shaft with teeth cut into it on the opposite end of the shaft to drive the spool. These shafts might also be about 1.5 inches or a little larger in diameter, I think. Whatever method we use to drive the spool should be kept above the spool, to maintain the ground clearance and be as efficient as possible. I have chosen a 1:2 ratio (1 input revolution for every 2 output revolutions) and I would like to keep that, if possible, but I am open to other suggestions. I plan to increase the input RPM at the transmission input by a factor of about 2 for the reduction of torque and using more standard parts and sizes. This will work with diesel engines very well, I think. This 1:2 ratio would match that RPM change so that the axle shafts are at engine RPM. I want most of the gear reduction to be in the portals, for various reasons including smaller diameter shafts and larger diameter portal gears that increase the ground clearance even further. Any ideas, suggestions, hints, guidance, observations, critiques, etc. would be greatly appreciated. If you have questions please feel free to ask them.