AFAIK they all have them and if yours doesn't then it's either unusual in not needing any, or it's been wrongly assembled.
When I bought my car I was quite friendly with a Lotus specialist and aside from selling parts he was very helpful about telling you about weak points he'd found. The driveshaft shims were one thing he mentioned specifically and how I should always make sure that the yoke was shimmed tight to the inner surface. He was so fanatical about it that he'd check customers cars when they came in for service and I remember he said it was a "service item" as far as he was concerned.
I've never thought too much about the design because Chris was so adamant about it, I think it was something to do with the load on the diff bearings/driveshaft in cornering but I can't remember off hand other than he predicted dire consequences for getting it wrong.
Ever since I've just fitted as many shims as would fit, I simply pack shims until the roll pin holes are just fractionally "too tight" and then press the pin in place. Once the roll pin is pushed in fully it's a very rigid assembly. I don't know if that's right or not, but it's worked for me.
Nothing special about the shims, you can buy similar things at most engineering suppliers.
Brian
