Replace the accumulators first, then see how you like the ride before replacing the springs.

If you want to test the old ones first, remove the center fitting and poke a pencil in the hole. If it goes in more than about an inch and a half, they are shot.

If the rear end still sags, you may need to adjust the valve. If the rear end loses height overnight, then rebuild the valve.

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1981 300TD 310k miles
1970 280sel 172k miles
1966 230 Fintail 162k miles

"Where are we going? And why am I in this hand basket?"