Just shoot the bushings, one set at a time, with a good lubricant, see if it stops the popping noise when you drive the next day. If you hit all of them and it still makes the popping noise, its not the bushings.
Having owned my '87 truck for a really long time, I've found that any dust from trails will work their way into bushings and dry them up PDQ! That will make it sound like a loud pop when driving. Rains will usually make them go away, then come back with a vengeance--or a 1000 watt amplifier!
The oil will work its way into the bushing within an hour or two, sooner if you're moving the bushing while you drive. It will come back in a week or so, but will help you ID the offending bushing so you can pull it and either replace or grease them with moly grease or graphite powder.