DRAIN TAP (engine block)...VAR(1/2" UNF --- parallel thread)
DRAIN TAP (radiator).....TR2-4(BRASS ------- tapered thread)
DRAIN PLUG (block)...1500 SPIT(NOTE = BRASS ------ 1/2" UNF)
DRAIN PLUG (magnetic)..VARIOUS(Spitfire, GT6, TR and others)
DRAIN VALVE (as OE)......VOLVO(block -- PV/AMAZON/P1800/140)