In North Vietnam around Hanoi, there was little in the way of mechanization, at least in the areas we travelled. I didn't see any tractor rebuild shops, just the occasional welding outfit that fixed everything.
The economic engine in Vietnam is Saigon (locals don't use the name Ho Chi Minh City). Our tour schedule did not allow any spare time to lookup and seek out tractor refurbishing companies. However our trip to the Mekong Delta took us through Ben Luc, an industrial area southwest of Saigon. Here I spotted several tractor shops, so we stopped to investigate.
These outfits look like tractor graveyards that are piled high the tractor pieces, implements and attachments. These scrap piles are the inventory for replacement parts. The refurbished tractors are on display and consists of American, Japanese, and Chinese brands. I left out Italian although I did spot a Fiat 540 Special, but I don't think it was operational.
The refurbished items looked just like that, refurbished but not remanufactured. Parts had mismatched colors (some were crudely painted with a spray can), welds were very poor, some fasteners looked cross-threaded or loose, electrical wiring was scary, etc. This level of quality is typical in SEA, where most machinery is just barely operational, but somehow they keep them running. It appeared that these tractors were for locals, not for export.
Nobody at these shops spoke English and our guide said they were all "workers who didn't know anything", so we couldn't inquire about their operations or prices. I think the guide just wanted to get out of there - this stop was just too "far off the beaten track" for him. Of course these outfits are probably not [the ones who provide export tractors].