They are not a polish rebuild, they are the last "super" series, model year 2002. They looked a bit more modern however the Slovaks didnt do a thorough job: They simply slapped full plastic bonnet wings around it, without checking the cooling capacity with the restricted air flow along the engine. The fan pushes the air through the radiator but it was caught under the hood along the engine.
Next to that, the synchromesh was weak, with a relatively rough operator it would jump out of 2nd gear at 3000 operating hours. You had to baby it to keep the synchromesh apiece.
the Ursus variants, built and developed in Poland did not seem to have this problem, the local contractor praised his Ursus, except for noting that the rear axle was too weak for this tractor.