If you want to replace a trailing arm I'd most certainly remove the subframe to make it easier for yourself. It might sound like much more work but the fixings for the trailing arms are a bugger to reach.

There's loads of information in this thread (largely thanks to Charmalu and dieseldan)

http://www.peachparts.com/shopforum/diesel-discussion/276507-rear-subframe-removal-bushing-replacement.html

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!