Supras don't have lifters in the classical, hydraulic sense. I don't know if this diagram will mean much.
What Toyota calls Lifters, are commonly called Buckets and Shims. They're all spring (mechanical) driven. If the engine has knock, depending on the severity, it'll either need a rebuild or (due to the price of a rebuild) I'd suggest a replacement. And while it's out a replacement of the headgasket.
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1988 Mk3 Turbo Targa - 17.5psi, 486hp, 494tq.
[img]http://www.**********s.com/supra/rsw_sig_stupidTN.jpg[/img]
Who came up with this 500px wide BS?