I didn't run any thrust washers on my first 2 topend. First one knock the pins out of the piston that hold the rings  in place. Which it quit running. Second top end crack the shrit and knocked the pins out were the ring end sit again. Also tore a big chunk out of the piston  between the rings.  So take it from me use them and buy the billet washer and the rm bearing  or you will be throwing money down the drain. Build it right the first time or you will regret in the long run.