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way when it comes to looking after those all-important pennies There was a time when the discerning operator was also a self-taught mechanic and unwitting expert. Every weekend they'd have a Gardner engine in pieces in a dark, damp workshop to sort out a 'banging', replace a worn cog, or remove a worn clutch.
So when this fella, let's call him Bob, came in looking for a tractor to run up and down the motorway, I certainly wasn't expecting the Spanish Inquisition. He knew what he wanted; something with 430hp, 2,100Nm torque, automated transmission (drivers wear out clutches quicker than my patience, he noted), closer to 11 litres than 12, a sleeper, three years old, not fussed about warranty.
Then Bob asked: "What's the diff?"
"The diff?"
"Aye, the diff. I don't want a final axle ratio too short, revs'll be up around the 1,500rpm mark at 56mph, drinking fuel like it's going out of fashion," he replied.
I didn't know, I'm not sure of the last time I even discussed diffs or final axle ratio. I reckon it's been 20 years since we replaced one, and that was only because the teeth were so worn on the crown wheel it felt like a 'slip gear' on a Raleigh Chopper push-bike.
I dragged up the specification from the manufacturer and saw it was specified with a 3.08:1. He then asked about the tyre sizes, I went into the yard and checked, they were 295/80 on R22.5.
Bob fished out a calculator and a piece of paper, tapped in some numbers, then frowned. "I reckon it'll be working at 1,400rpm, just a tad below, at 56mph... I need something closer to 2.79:1 to get the revs down on the motorway, saves fuel that does. Suppose it'll cost to replace the final axle ratio... second-hand one will be upwards from E600."
"Yes," I replied, "probably."
"Well," he said as he prepared to go, "I'll leave it for now, cheerio."
Someone, less inquisitive, bought the truck. All he did was kick the tyres.