Classic Truck: International S-Line

The International S-Line proved a trusty workhorse in the 1980s and ’90s, and there are many still working away. Matt Wood rekindles some almost-forgotten memories



It’s always been seen as an insult to refer to someone’s vehicle as a ‘farm truck’ in fact some even get a tad upset. But really if you take a step back the ‘farm truck’ label is more recognition of the vehicle as being a survivor, and a badge of reliability and durability.

Invariably, old Internationals cop the farm truck moniker more often than most, and invariably it’s the pre Iveco badge Acco that steals the farm truck limelight. However, less obvious but no less a survivor is International’s venerable S-Line.

When the bonneted S-Line first rolled out of International’s Dandenong plant in May of 1979, the driveline choices were initially limited to the 7.64-litre International DT466B, the 14-litre Cummins NTC230 or Cummins Formula 290, Formula 350 and Cummins NTC350 power. Also offered were transmissions from Eaton and a Dana 3.75 final drive.

The new range superseded the outgoing Transtar 4200 and 4300 models and was set to cover roles from medium-duty vocational to heavy-duty line-haul with a maximum gross combination mass (GCM) of 54 tonnes. While the sheet metal and design was shared with its American IH cousins, the S-Line was developed for Australian conditions with high tensile chassis rails and was considerably beefed up for the local market.

Prototypes clocked up in excess of a million kilometres around International’s Anglesea test track. Myself, I can’t help but fondly remember the S-Line as the best truck I ever fell out of, something easily done if you didn’t take care to hook your foot under the 2.28m wide cab as you were climbing out. Even after a fair bit of time behind the wheel of one I still managed to arrive at ground level with an undignified plop on occasion before brushing myself off and hurriedly looking around to make sure no one was looking.

In the United States, conspiracy theories run rife about the government’s mysterious Hangar 13, supposedly home to a crashed alien space craft. Aussie truck drivers, however, have a conspiracy theory of their own, and that is the alleged existence of SETI (Secret Engineering Team International) which had its headquarters in a mysterious shed at International’s Anglesea proving ground in Victoria.

This team of engineers specialised in finding the most inconvenient location for the top step of International trucks, the finished product often resulted in an unsuspecting driver being left scrabbling like a puppy on a new lino floor as they left the cab backwards, often collecting their chin on the driver’s seat on the way out.

This engineering team also allegedly pioneered research into the ‘self-loosening nut’. This nut was primarily used as a fatigue management tool. When used on the passenger side mirror housing of an International truck, a driver could glance into the left-hand mirror in the middle of the night to be confronted with a ghostly green dash-lit face glaring back at them, a result of the mirror bracket slowly folding back into the truck while in motion until it was facing the driver. The resulting yelp of terror and jolt of adrenalin could keep a weary driver going for hours afterwards as they nervously peered back at the eerie apparition in the passenger side window, or until they stopped and tightened up the self-loosening nuts on the mirror bracket.

As an aside it’s also widely believed that Ford trucks used these nuts exclusively to build its entire Louisville range during this era, hence the nickname ‘Looselybuilt’.

The early 2600 S-Line family models shared the same sheet metal as their International Navistar cousins in the US with a tall blunt squared off grille high front guards. In fact, clearance between the steer tyres and guards was such that a lazy person like me could actually lean over the steer tyre to access the dip stick and check the oil without dropping the bullbar and raising the bonnet. Although this tended to be a false economy if you actually did need to top up the oil and it did give passers-by the impression you were being eaten by the truck.

Testament to the longevity of the S-Line is that the Australian Defence Forces used the vehicle as a B-double and heavy haulage prime mover and also in road train roles for nearly three decades. In fact the ADF are only selling off the last of their N14 Cummins powered Internationals at present, with replacement MAN prime movers on the way.

Soldering on

The S-Line soldiered on in Australia while the pains of corporate restructure back in the US became symbolic of the ebbing fortunes of the International Harvester brand back home.

As with so many other long-standing American industrial manufacturers of the time, the IH badge that had once adorned everything from tractors and refrigerators to pick-up trucks and buses was struggling by the mid-1980s. The American parent company became Navistar International in 1986 while here in Australia International continued to pump out tough, honest and dependable workhorses even after Iveco came on board in 1992, becoming International Iveco Trucks Australia before finally dropping the International name in favour of Iveco in 2001.

The S-Line was to become the mainstay of many large Australian fleets through the 1980s and into the ’90s, and could be seen bearing the livery of the Scott’s Group, K&S Freighters as well as Simon National Carriers to name just a few. The full-width cab provided a huge amount of wiggle room and an integrated sleeper provided a comfortable place to camp for the night.

Noise suppression wasn’t fantastic on early models with early day cabs even having the gantry-mounted exhaust right behind the driver. The prime mover developed an enviable reputation for hanging together in some punishing circumstances even though the interior had all of the acoustic characteristics of a hayshed in a hail storm.

A model update in 1991 saw the introduction of the S-Line 3600 as well as the imposing higher horsepower, high GCM Transtar 4700 based on the S-Line cab. This update saw a new aero look front, a redesigned interior and also the introduction of electronic engine management by way of the new black Cummins M11. The new model became the pinnacle of the S-Line’s success and by the mid ’90s, the Dandenong plant was churning out around 500 units a year as well as a further 100 4700 Transtar models.

In 1993, the introduction of the Series 60 Detroit was offered as an alternative to Cummins power and the Detroit quickly became a hit with both drivers and operators alike. The ’90s also saw the introduction of the base or fleet spec 3300 as a budget offering. The 3600 S-Line became hugely popular, mainly due to the rugged dependability of the International design. GCM’s had climbed too during the S-Line’s existence up to 102 tonnes, with heavier duties handled by the larger Transtar.

The Transtar 4700 was based on the S-Line, both sharing the same cab sheet metal but set 200mm higher off the chassis. The Transtar also featured a set forward steer axle as well as longer front suspension travel than its lighter spec S-Line cousin. To match the raised cab a taller bonnet was fitted to accommodate and cool the N14 Cummins, which by the end of production gave the Transtar 525 horsepower and a GCM of over 120 tonnes.

In many ways the imposing looks of the Transtar were the ultimate expression of the S-Line ethos. As legal gross weights had climbed during the ’90s, so too did the Transtar’s popularity.

The sun started to set on the S-Line family in the late 1990s with the introduction in 1999 of the bonneted Iveco Powerstar, which bore a whole new Euro style approach to the role that was being filled by the S-Line. As the Powerstar rolled of the assembly line, the S-Line continued to do so alongside it for another 12 months.

Many classic trucks of other brands are now showing up at historic truck shows and rallies but you see little written about old S-Lines, and they are rarely seen on display. I asked one industry insider about this and he replied quick as a whip, "Well of course, they’re all still out working for a living".

In our market that relies on second and third life and beyond usage of heavy commercial vehicles, the bonneted Inter can still be seen in any number of roles from tipper and livestock haulage to local wharf work and beyond.

The S-Line pictured typifies the later 3600 model. I found this one at Brad Drew Trucks in Fyansford, Victoria. It’s equipped with an M11 Cummins and backed by a 13-speed Eaton RoadRanger while riding on Hendrickson air bags.

It had been many years since I’d been behind the wheel of an S-Line and the memories came flooding back as I fired up the Cummins under the bonnet. And yes, I even nearly fell out of it when I parked it.

Click here to find an International S-line 3600 truck for sale.

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