hey scooter, buddy, truth be told, you cant run 44s on a D44...reliably, yeah you can drive it around on a D44, but muddin it you not going to be able to
trust me, ive been thru a jeep D30 and a ranger rear for my first SAS, this second SAS has a D44 and 14bolt rear, and the third one that is going in is a D60 front with the 14 bolt rear, which later on i may goto a D70 or D80 just to be safe, so i will be one of the few on here with a 1ton equiped explorer
as for the 46's are you talking about the mickeyT claws that the 46 size just came out in
as for the power required, it is possible with the 4.0 your just going to need to gear the axle right, most likely a 4.88 or 5.13 with a 46, roughly for a 39-44 is going to be 456-488 for gear selections, and also a heavy duty clutch(i have a ceramic in mine)
but if your going that big, you might as well go rockwells and be done with it, figure $1k for a pullout set of rockwells, another 800-1k for wheel brakes, whatever it costs to convert it over to leafs, front chevy springs are gonna cost about $300 for the pair, plus whatever the rears cost ya, plus about $100 for the perches for the axle, and then steering, ive been down the road of lifting my explorer a few times, after this lift, with purchase of vehicle, i will be in about $8k(and the truck was only 2200)
figure i would chuck in my few coins