Can early struts swap with our later ones?

[DesktopDave]

I was searching for this...couldn't find it.  Our 51mm struts are wider than the early e30 45mm.  Can they still swap with the early ones if I grab the whole housing?  What difference is there in 5mm?

I found a nice set of bilstein sports in an '86 diving board e30...but I'm suspecting that they won't fit.

Now I'm confused.  I measured my 1991 318i 4-door (build date 8/90) and the struts are about 2".  I'd assume that's the 51mm housing.  When I measure the struts I pulled off my 87 325is parts car, they're the same 2".  Can anyone explain?  Does the early M42 sedan have different struts than the later 318is and 'vert?

[tom d]

the struts are interchangeable. i just did this, putting 51mm 318is struts onto a 1984 318 with 45 mm tubes. everything fits, brakes and all, however there might not be a bracket for the abs sensor wire.

the 1987 325is came with 51mm struts.

all M42 318s came with 51mm struts