I would like to find a living graduate of Erasmus High in 1947 who
knows Arnold Levy personally - and can tell me more about him.  He
changed his name to Lawrence Dickert after a while - and moved to
Florida.  If you can help me find someone in New York City or the
surrounding burroughs - that would be exceedingly helpful.

You will not get a direct address of a private individual on G-A.  It
is against the principles.

I checked on this site for both names:
http://ssdi.rootsweb.com/cgi-bin/ssdi.cgi

THis is the Social Securities index of deceased persons.

There were 20 Arnold Levy (none with the middle name Lawrence).
There were two Lawrence Dickert: one born in 1930, SS card issued in
NY, died in 1997 in Ft. Lauderdale.
The other was born in 1938,  SS card issued in NY, and died in the Bronx in 1994.

My apologies for this negative search effort.
Since you are looking for someone who knows or knew the person, if you
think that he may have passed away, perhaps a search for an obituary
listing survivors or others could be a help, but again, a direct
contact could not be posted here, unless that person were listed on a
website.

But who knows?

Let us know if you think this could be the case, and how you would like to proceed.