3 puppies is right. you need to know your production date because 68 was right around when toyota went from ball and claw to birfield. if you are ball and claw, you will have have to swap inner axles, which will not match your side gears and you will have to figure out sealing where the inner axle seal is.
if you get a 76-78 disc setup, you can swap fairly easily into an older birf axle, but you've got the weaker and harder to find parts (small pattern disc knuckles, long birfs). the easiest disc stuff to find is going to be the mini truck which will require your first mod of grinding out your knuckles to fit the birfs. from there, you run into brake line issues. drums have one line splitting out to each front tire and the rear axle and are a smaller fitting at the hardlines than disc. disc has one line for the front and a seperate line for the rear axle
and yes, you have to deal with a boosted setup, which means modifying your firewall or using a spacer that sometimes doesn't work with your manifold setup.
rebuilding your drum cylinders is cheap, easy and requires a bit more maintenance (when you start noticing the brakes aren't as good, you have to adjust your cylinders, which can be a pita).
