Chris,
Congrats on your new project..
The 5748 has the older 5501 engine from the 5511. All the 55, 56 (with cab) and 57 tractors have this engine, with a bit higher
compression than the other 4 cyl. with the same bore x stroke.
I think the rear wheels are no
Zetor ones at all, even the flange looks different.
That front axle was first adopted on the 5545, somewhere late 60's. The 6745/48 was the first with the heavy duty planetary axle.
The 5245 was usually sold with the lighter duty front axle, that shared the front hubs with the axle of the 4wd orchard model 5243. In some countries the 5245 also has the planetary axle, and in other countries the 6245 also had the light duty front axle.
For the 5245, the static load rating is 1800 kg, so the max load with front loader would be somewhere 2.5 times as high, (usually factor 2.5 when speed is reduced to below 10 km/h ??) about 4500 kg. That makes it possible to lift max. 1600 kg on the loader.