
we have 2 tractors quite the same that have the hill climb, ones an older possibly early 90s renault 106.54 turbo with a 30k gearbox, the newer one is a 2001 renault temis, with a 40k box.
the older one is slower on a flat road because of the slower box, but up the hill i can take the 106 up the big hill fully loaded in 4th high (top gear), the temis even when not loaded requires being slurring through the gears to get up the hill, its got a narrow power band, so its a case of going through 4 gears and the half gear.
The older one is also easier on the diesel.