Thanks for the prompt response. See error message below.
I know I can work around by referencing busybox directly.
It just took me a few minutes before I realized that the issue may have been with the version of mount in util-linux.
I had installed it a couple of days ago but had not actually rebooted the vm and needed to remount the host shared drives.
It was momentarily concerning to see the error...
my first thought was that I had inadvertently hosed the host drive.
tc@box:~/Downloads$ tce-load -i util-linux
tc@box:~/Downloads$ sudo mount -t vboxsf vbox_shared /mnt/vboxsf
mount: wrong fs type, bad option, bad superblock on vbox_shared,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so.
tc@box:~/Downloads$ dmesg | tail -10 -
[574390.649627] floppy0: no floppy controllers found
[574390.649661] work still pending
[574394.056671] floppy0: no floppy controllers found
[574394.056722] work still pending
[574396.907809] e1000: eth0 NIC Link is Up 1000 Mbps Full Duplex, Flow Control: RX
[574397.166595] floppy0: no floppy controllers found
[574397.166656] work still pending
[574483.904510] vboxsf: Successfully loaded version 5.0.18 (interface 0x00010004)
[574493.988213] sf_read_super_aux err=-22
[587816.688115] sf_read_super_aux err=-22