Our 24 row was an early 1770 and it wasn't built heavy enough, basically they took a 16 row and stretched it to a 24 row, our 12 row 7200 required welding too but not nearly as much as the 24 row.  Also the 24 row had a hydraulic system that was a joke and it was a never ending fight to keep it phased right and not settling on one side or the other.  We would go through our 7200 every winter and had very little trouble with it in season but the 1770 seemed like it always had something wrong with it.  We ran the 7200 for 7 years and every year we always had one or two days we could get 200 acres planted, I think we had three 200 acre days in the five years we ran the 1770.