Six bolts.. 4 under the axle ( 2 on each U-bolt) and one on each end of the spring.. You can put a jack or jack stand under the axle to hold it up.. Replace the spring and retighten the bolts..
I generally would have removed the U-bolts first and then the spring hangers... Be sure to check out the shackles for wear..
Less than a six pack job even with a buddy helping..