The 3680 was equipped with a Valmet engine in 1990
10 HP more powerful model 3690, and at the same time
A 3670 model was available with a 6.6 liter (170 hp) Valmet engine. In 1992, similarly to smaller models, the gearbox was changed to a preventive one
in the four-speed Dynashift high-speed gearbox
. In 1994, the 3690 engine was updated to a newer one
model 634DS.