Guido Rössler (and Schocki), active on the German Porsche Friends Forum PFF made this description for replacing the timing belt, seals, and the timing belt tensioner.

Porsche 928 Zahnriemenwechsel + Porkensioner + WaPu + LiMa + Ölpumpe + WDR-KW + WDR-Nockenwellen tauschen.docx

Porsche 928 Zahnriemenwechsel + Porkensioner + WaPu + LiMa + Ölpumpe + WDR-KW + WDR-Nockenwellen tauschen.pdf