I've always used luk in the past with no problems to date...the last kit I bought a couple months ago for my '86 2wd with 4.3L and 3sp (same clutch setup as 465 though...12"..she lasted 145,000mi!!), and the throwout bearing had a "plastic" sleeve, but the area of contact with the pressure plate and the innards were still steel. I called them up to ask, like you, WTF, they said in testing the composite (not really plastic) sleeve held up better in testing, with less fork wear, then the steel version..I installed it, no problems so far, she's my daily driver, about 10,000mi on it thus far..holding up well...I wouldn't worry about it...the composites they have today are very weel engineered..