Indeed, it is a 355 series truck. This does not have the pedal supports on the large clutch cover.
I could see that the hub did not have 6 bolts on the transmission, it only has 4 bolts. Anyway I kept going, it was not possible to push the pilot shaft. It seems that this model does not have a sliding pilot shaft.
If I could see that when starting the truck the hydraulic pressure pushes the crapodin against the pressure plate, then my face was filled with hydraulic fluid!
The spring that brings the fork to the transmission is not original, perhaps that spring is very small and the hydraulic pressure acts on the clutch and causes it to slip.
I don't know how to insert photos.....