Malaysia 1967 $1 Z/1 Replacement

***How time flies, yes, for this banknote is already 55 years old, much, much older than all you neophyte collectors out there.
But though half a century old, it's still holding its own with a firm and crisp paper but sadly its condition is only, maybe, About Very Good only, ya, do judge the banknote by the scan, like they always say, "because I am not a professional grader & I don't want to misslead(sic) anybody"...........
How come there were no Replacements for the 1967's $1,000 deno or say the $5 deno?
Yes, the answer is actually very simple, ie, all the notes for the $1,000 & $5 denos were printed perfectly, all scoring a perfect 10 & as such, none needed to be replaced & thus, the prefix of Z/1 for these denos became superfluous.
Yes, that's a perfect 10 answer for why the $1,000 & $5 1967 series had no Replacements, unless, of course, as usual, some Smart Alecs out there have a better suppositioned answer.........