How big of a job is it to change leaf springs??

It's not hard, but to make things easy, buy new rear shaklesw/bushings, and new U bolts at the same time. Then you can just cut the old ones off(u bolts), unbolt the front hanger bolts, onbolt the rear shakles, and heat the studs with a propane torch..They will slide right out. with minimum fuss. It's hard if you dont have shop air, to remove them by unbolting and reusing everything. Much easier to cut them off.