Strut housing measurement?

[Hussbuss]

So, I've been keeping my eye out lately for upgrading to Bilstein Shocks. but I've heard from some people that there's two different strut housings... one is 45mm and the other is 51mm.. So I go out to my 84 E and measure the front struts. I measure several times just to be sure. Here's what I come out with:

Strut Housing Outer Circumference: 6 7/16th's

6 7/16ths as whole fraction is 103/16 which is 6.4375"

The formula for Diameter is " Circumference / Pi "

D= 6.4375" / Pi = 2.04"

2.04" = 51.816mm

D=51.816mm (There's some dirt on the outside so I figure its 51mm)

But I heard a while back about some of the late models having 45mm instead of 51's. Can anyone help me with this?

[TimeMachinE30]

Use a dollar bill and, long ways...perpendicular fashion....wrap it around. If the ends touch, smaller. If a small gap, bigger.