I already had a Monarch electric pump from another project so I bolted it to the frame opposite from the air tanks.
This is the pump I used.
http://www.piercewrecker.com/12_volt_pumps.htm#PM-319-6P Pump
The 6qt tank was just big enough for the one big ram.
It was an easy install. Just one hose made by the local NAPA.
Its a 12v pump , so since I have two 12v batteries in series on the truck...
I wired the pump to the low side 12v battery and chassis ground.
Its no problem loading just the one battery because lead acid batteries
recharge well in series even when one is healthier than the other.
Its when you put them in parallel that you get big problems.