So, I finally paid a bit more than needed and got one of these.
First type German G-3 stock.
The rails are about 3/4" longer than the newer pattern stock arms, so it makes shouldering the rifle EVEN MORE comfortable.
The A-3 stocks are "cool", a "must have" for the true HK addict, but unless you're in a Leopard Mark I on the Fulda Gap circa 1975, pretty useless.
The housing unit is heavier gauge than the newer type, the rails are a bit cruder, machining wise, on the inside, but overall, it is sturdier and you could beat a door down if needed.
Pics of it and the newer type for reference.
Just thought I'd share on the off chance someone else is thinking of getting one. They used to appear about once a year on GB, there are now a couple on there and I've probably seen a half dozen on there the last several moths or so.
Someone must have unloaded a conex full somewhere and made them more available.
First pics on my PTR-32, poor mans HK-32.
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Newer pattern top, early pattern middle, German MP-5 F stock arms bottom.
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Comparison of later pattern, top, and early pattern, bottom.
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Is that Malaysian AF pattern or Rheinmettal's iteration?
Interesting.

Indonesian Air Force pattern collapsable stock



Note the unique pattern on an HK54 and HK33 in this H&R Flyer