They will fit but not without mods. And J10 axles aren't 3/4 ton, they're 1/2 ton. Nearly a foot wider, rear perches must be moved in, front springs must be outboarded. front needs to be from a 74 to 79. The back can't come from a quadratrac truck.
As long as the rear is centered, it should be a good upgrade. Those axles are most likely 8 lug so you'll need new wheels & possibly new tires if you have 15" wheels. Most 8 lug calipers are too big for 15s without some grinding. I would look for some wheels with a lot of backspacing (like H1s) to offset some of the added width.
What tire size are you running now & what do you use the Jeep for?