I've got a 5' land pride 1260 and really like it. Havent had a time yet that it bogged the tractor down and I've cut about everything I see with it. I cut level, hills, banks, etc with it.
The stump jumper, I think, is a plate under the blade mounts that allow them to skim over rocks and stumps and not tear it up, like a skid plate sort of. The blades may still hit them but you'll know it if they do.
Shear pin is just a low grade bolt that will break if the blades REALLY jam into a stump, etc. if this happens you put in another shear pin (low grade bolt).
Other type is a clutch type that allows the joint between the driveline and gearbox to slip in the same scenario. Reportedly they require some setup and maint but lots of people like and use them.
I got mine with a shear pin. I didn't want to fool with the maintenance of a clutch and my thinking (may be wrong) was that if I hit something that would make the clutch slip, I'd rather a shear pin brake and I KNOW I just hit something bad and can get it out of the ground so it doesn't happen again.
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