There are some differences
MDF99:
I have a '99 Ram gasser w/ a Hellwig setup. All of the airlines feed into the cab w/ a tee on the compressor (no air tank) with the lines into lines feeding the airbags. The compressor is switched off the ignition, automatically comes on if it drops below 5 lbs. Works good, never had a problem since '96.
I actually haven't installed my controller in my 2000 diesel yet. I bought Airlift bag only kit and have filler valves installed in my receiver hitch bracket. Reason I didn't buy whole kit is I have Hadley airhorns w/ a compressor and air tank. I bought an Airlift dual gauge/fill kit from Ricksons. I'm going to modify fill switches to eliminate the compressor control lead. I will have two silinoids with the fill side tee'd to the air tank. When I press the fill for one side, the silinoid will open, apply 125lbs pressure from the tank and when pressure drops in tank, compressor automatically come on.
So, yes there are differences.
Wiredawg