In the 80hp range.
The 188 was a good very basic tractor that was becoming out dated by the end of the seventies.
The 6600 was a poor tractor when compared to the 7600
The 784 was a soft tractor when compared to the 844, and that stupid 8mm pin holding up the lift still haunts my dreams.
I never remember any Zetor doing big hours around here trouble free, had a 6cyl Ursus equivalent and it didn't give good service.
The Deutz were a good tractor, but my god were they noisy, if the wind was in the right direction you would hear one 3 or 4 miles away.
The JD 40 series were a good tractors, but mainly 1980's and the 3140 is 100hp 6cyl, isn't it?????? The seventies JD's were good tractors, but good mechanics for them were hard to find.
In a similar vein, the Fendt favorit 600sl, 90hp 6cyl
MB trac 800