"We stripped it down completely before we completely rebuilt it," he said.
Mr Musson said his company has 11 similar log haulers dating back to the late 1970s.
"The technology has changed within the last 30 years, so rather than buy brand new machines costing anywhere from $1.5 million to $2 million, we're rebuilding our entire fleet.
"This is the first we've done, sitting down with engineers and saying this is exactly what we want and working to a budget," he said.
FOMS had intended to tender out the other log haulers for their refits but was so impressed with Garmac's skill they are not going to bother.
"It's completely exceeded our expectations and we're rapt. There have been problems these guys at Garmac found along the way but they have always come back to us with a solution," Mr Musson said.
FMOS has between 35-50 logging crews working around the North Island and owns the haulers and leases them out to the crews.
"This machine is the baby, really, as it weighs about 30 tonne. We've got others weighing up to 75 tonnes. The next one coming into Garmac for the rebuild weighs about 62 tonne."
Gear added to the machine includes new hydraulics and controls. All that needs to be fitted now is about 5 tonnes of cable to haul the logs before it is trucked to work in forests north of Auckland within a week.
Mr Musson said it was a feather in Garmac's cap because they had never worked on a cable hauler before, "but they've come up with some really great innovations".
Mr Williamson said it was a daunting prospect, but once they stripped the machine down things fell into place.