Thanks all,
I have heaps of thread engagement (2/3). I did the nut up nice and tight by hand and another 1/4 (approx) by belting on the slots (everyone says just nip it up, not to tight). Test drove yesterday and today with no clunks.
As I said, the bilstien is slightly longer (maybe 1-2mm) in the body. Comparing where they sit in the tube, it is slightly higher than the top of the tube (1mm) while the original was slightly lower. The big difference I can see is in the design of the retaining nut. The bilstien is a larger diameter body than the original so the threaded section is thinner. This is turned over to make the bearing surface (on the strut body) and spot welded to the top plate. This means the top plate also sits higher with respect to the bearing surface.

I just can not see how I could have done anything different. If I take the spacer out the shock may rattle or damage the base of the shock.

BTW do you guys re-install the rubber boot, Bentley says discard it when replacing original gas shocks?

Thanks again
Karl

You will likely notice a 'klunk' when truning sharply or going over bumps...try on a speed bump at 5-10 mph. I think I've heard that Bilsteins require bushings to make up for the 10 mm difference from stock...sorry to deliver the bad news..I'm sure others know more about this than I do, but encountered the same problem on a 244...after the bushings...solid and quiet...good luck.

-Dee Jay

I am in the middle of replacing my strut cartridges (left side is done, doing the right side tonight) and I wondered about this too. I believe Paul is right on the money.
I found this in the archives. Read the response from Steve about halfway down. Look for, "One thing to check..."
From this I take it that you should not be able to screw the retainer down all the way. There should be some threads showing. But 10mm showing sounds like too much although I can't say for sure. I don't think mine was showing that much thread. I get the impression some people leave it too loose and it can back off to the point where the cartridge will start clunking up and down.
I don't know what tools you are using but it seems to me that without proper leverage you won't be able to get this tight enough. I used two pipe wrenches with a two foot length of pipe on each handle to snug it up real good. But don't force it. It's a matter of feel. I think it could be easy to over do it this way. Please be careful if you go back in there for this.
I am not a professional mechanic and my comments are based on my own observations having recently engaged in this procedure. I trust someone will correct me if I am mistaken in these assumptions.

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1980 240 DL

If I'm reading this correctly, you simply have encountered a difference in cartridge length between the Volvo strut carts and the Bilstein. As long as the cart is well captured, you have sufficient thread engagement and the nut is tight as hell, you should have no problems.

*see disclaimer in other post about changing shocks/struts.
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www.fidalgo.net/~brook4