I had problems with one of these, as a result of the different location of the diaphragm pivot point/ring
(moved outwards compared to original clutch cover) they need a longer throw of the release bearing to fully release them from the plate.
Why they are sold? Good question, probably the same answer as to why inferior bearings are being sold [}:)]
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<font color="blue"><i>1980 TR7 DHC (my first car, now restored and back on the road)
1981 TR7 FHC Sprint (better known as 't Kreng)</font id="blue">
<b>[url="http://www.tr7beans.blogspot.com/"]<u><b><font size="2"><font color="red">My Weblog</font id="red"></font id="size2"></b></u>[/url]</b></i></center>
