I'm not convinced this is a problem that needs sorting. There are after market gearboxes that deliver torque, scale speed and smooth quiet running to varying degrees depending on your budget, from the taigen steel 4:1s which are robust and provide scale speed, going up in price you can get them with bearings making them smoother, there are Mato steel gearboxes with bearing which are similarly priced but arguably more refined. Then at the top of the price range you have the ETO gearboxes, the model spiegl ones and the dklm triple diff ones. On the scratch build side there's a chap called Robert tanzer on the Facebook world rctank group who makes his own with initially with belt drives but now using planetary gears into beefy bevels on the final drive which are amazingly quiet and very strong.