4 half tracks requires a total redesign of the powertrain. You will have 2x the driven axles. Plus much modification of the hull, controls, etc.
This is not a simple modification of existing chassis. You might as well design a new vehicle.
Yes and no. The reason to *not* design a new vehicle from scratch is that we've got some 2,000 M1's sitting around collecting dust. That armor and engine is expensive in both time and money to melt down and reproduce in a new vehicle.
Yes, power has to be transfered to the new forward half-tracks if we go with a 4 half-tracked approach rather than stick with the original two track design...but there are *multiple* ways to transfer power to the forward tracks, all of which would be worth exploring (hull modification for new drive shafts as you mentioned, external drive shafts, chains, electrical power transfer to two near-freight-train-sized electric motors, etc.).
5 Legislative Days Left Until The AWB Expires