It's an easy job & should only take you about 30 minutes per side & that's stopping for a tea break
The hardest part is getting the old ones off...the threads will be rusted & this will stop the nuts coming off easily. Some of the drop links have an Allen key hole in the end of the ball joint shaft so you can hold it from turning while you remove the nut, but in practice this only works if the threads are in a new condition.
The preferred method is to use loosen the nut as far as you can before the ball joint starts to spin & then use an angle grinder on the shaft or nut & cut through it.
Another method is to use a blow lamp to heat the cups of the ball joints on the drop link...this melts the plastic & then they will easily knock off the ball...then the ball can be held with a pair of stilson's & the nut undone...this is the method I have used a few times & it works a treat.
When you put the new link on & the nut is done up coat the threads with some grease...this will help to stop them rusting & you will be able to get them off easily if you ever need to remove them for any reason.
Good luck.
Cheers.