The Alignment Cage can be left in place with the old-style "non-dammed" vacuum pump gasket. With the new style "dammed" gasket, the cage must be removed as it interferes with the "dam".

If you remove it, hang onto it. They're expensive to replace and make life a lot easier if you have to pull the IP.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]