>This seems to depend on the drive. TZ87 is DLT-III, and is officially =
backwards
>compatible to TK50 and TK70. You can insert and read those tapes there =
without
>any problems.

But the very similar TZ87-N lost read support for
TK50 and TK70. I presume that this was the result
of cost-engineering the thing to make it cheaper.
It may be that the mechanical mechanism changed enough
to cause problems: I don't have one and I'm not
sure I'd be willing to try this if I did :-)

Antonio