There have been a couple of theories about the coppery-pink (which I assume is what you're referring to as "pink") shocks ... that they identify "competition" shocks or they are rebuilt units:
The lower shock in these Elan adjustables are what I think the color you've mentioned:
From Peter Caldwell of Worldwide Imports:
"
Paint:
Beginning in 1968, Armstrong "rationalised" their part numbers for cataloging and packaging and labeling. They essentially whittled the range of all shocks (tube, struts, and levers) into 4 groups.
Painted as follows:
"All units above AT9 and Super 64 size - Black
All AT9 and Super 64 size - Bronze
All Roadholder Struts - Bronze
All others - Blue"
This is from a publication "4E 1st February 1968 Product Information"
The RX casting is a bit of mystery, but we have noted that there is a change in the valve threaded port in so far as the seal and washer arrangement is concerned. RX shows on all of the lever product castings, and by assessing the date codes, seems to have been started around 1964 or so.
There's a myth that floats around every few years that the RX means rebuilt, but it's real hard to retroactively cast letters into a body. Also, you'll find some models of lever shocks in Bronze. It is indicative of piston size and applies to the tube shocks as well.
The natural body and painted (Parkerized?) arms would seem to be the way the shocks were delivered to the assembly plants. Often rears were then fully painted over "on the line", but that's conjecture from some assembly line photos, and may not be consistent.
All good stuff.
Peter C "
And from Rich Chrysler:
"Over the years I've observed a lot of copper coloured shocks on big Healeys
and other BMC cars of the '50's and ;60's. I have never been able to prove
these to have been installed originally, but have often wondered as to their
identity or meaning. Some folks have a theory that they may have been part of
the BMC "Gold Seal Factory Replacement" scheme of the period. However, I've
seen Gold Seal remanufactured items and they were painted gold, not copper.
Recently I was talking to a friend who was born and raised in the town of
Abingdon, in the U.K. and in his early driving years often visited the
Abingdon Competitions Department on Saturday mornings where one could purchase
factory approved items right there over the counter. He tells me that the
copper painted Armstrong shocks indicated they were revalved and were
considered a heavier duty shock for competition work, and he'd bought a set to
upgrade his '65 MG Midget. A chum of his bought some to upgrade his '68
MGB/GT, and so on.
Why I'm asking this now is that I'm currently doing a restoration on a
relatively low mileage '54 BN1 that's been off the road for over 40 years. It
has a virtually fresh full set of copper painted shocks, and I'd hate to be
changing this out if it's a legitimate part of the car.
Has anybody else any experience or comments about this? (Yes, I know what it
says in the Concours Guidelines.)
Rich Chrysler"
I think it's one of those unsolved mysteries.