I just did this on my 84 SD
I decided to to everything at once, so I dropped the whole subframe
using three jacks: one under the diff and one under each trailing arm.
I got all the rubber parts from the dealer, so, hopefully, I will never
have to do this again.

Good Luck with your project,
Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end