I got my 5.0L falcon converted to LPG by PARNELL Gas
They are up in Laverton and they do an awesome job. Only took them 1 day to do mine and it was a very neat factory install.
From memory I had a 70 useable litre tank, factory fuel gauge also doubled as an LPG gauge
Cost was about $2,400 from memory, so only about $400 after I got the rebate from the Government
http://www.parnell.com.au/index.php?option...7&Itemid=41