Diffs not working

["Adam P. Brodeur" <AdamB@net1plus.com>]

Hi all,

PLEASE HELP.  After installing an aftermarket radio in my 84 4ksq, the
center and rear diffs do not lock.  I took apart the dash to take a
closer inspection and grabbed the Bentley.  I think I may have cracked
the valve, but don't see any cracks.  What do you think could be wrong?
My father thinks it could be the return valve.  He said that was a
common problem on earlier Corvettes.  Any help would be appreciated in
getting the diffs working and the dash back together.

Thanks,

Adam