My factory parts book for 88-90 models appears to show two types of starter, a 1.4 Kw, which is superseded by a 1.1 Kw, for ALL varieties of 740 in that year range, regardless of engine type or anything else.

I suspect it is not so much what variety of starter the unit(s) that failed were, but who rebuilt them. Cheap, store-brand "rebuilt" parts, such as starters and alternators are not up to the standards of brand-name "remanufactured" ones, which, supposedly, are restored to new specs throughout, unlike the cheap ones, where the fault will be identified and corrected, (and the casing cleaned and given a quick shot of black paint) but all the other worn components are left in place if they appear to be working correctly. Then, six months later (or, after the warranty has conveniently expired) something else lets go.