nicopress sleeve for stainless steel cable

I have some questions regarding swaging stainless steel a/c cable with
nicopress sleeves. Specifically, several sources I've seen say that zinc
plated copper sleeves should be used on SS cable (I.e. 28-2-G for 3/32"
cable). Many suppliers that I know of sell SS cable and the zinc plated
sleeves, so presumeably there are a lot of aircraft out there rigged
with these sleeves.

However, National Telephone (www.nicopress.com) appears to require a
special tin plated copper sleeve be used for swaging SS cable ends
instead (i.e. 428-3-VG for 3/32" applications). This one appears to be
harder to find among various suppliers (though I havn't really looked
that hard yet).

My questions a

- what is the hazard of using the wrong sleeve on SS cable: is it a
strength or corrosion issue (or both)?

- what's the real story anyway? I.e. are the zinc plated copper sleeves
or even bare copper OK on SS cable, or ?

- where's a good source for the tin plated ones in the event that's
required?

I have some SS cables I made up with regular copper sleeves and am
trying to assess when I need to remake them with the correct sleeves
(i.e. immediately or when I get the materials). They appear to be as
strong as the galvanized cable ends I've made elsewhere so there's no
immediate problem that I can see.

But I do want to know what the correct sleeve is to be used, at which
time I do plan to remake the cables...

Thanks,
LS
N646F