Ryan:

You can buy valves for the tank at RV dealers--or RV
dealers on the web.

If you have the Autostop fill valve, replacing it with
a standard fill valve and a standard bleeder valve will
make life simpler--any propane guy knows how to fill a
tank like that.  Most do not know how to fill a tank
with an Autostop fill valve.

Similarly, you can replace the shutoff valve, too, if
it is worn--taking a really hard turn to shut it off,
for example.

See:
http://www.pplmotorhomes.com/parts/lp-gas/propane-refill-adapter.htm
for fill valve and shutoff ("service") valves.  This from a simple
search for "RV propane valve."  The little bleeder valve is about
$10.  So for ~$80 you have everything you need for your tank.

Search the archives for the last year for "propane valve" or such
and you'll find lots on this.  The last thing you need to do is
replace the tank itself.

                                Richard A Jones
                                Boulder, Colorado