I've got a 1971 Ford 4000 su and was wanting to know if the axle and cradle from a 5000 Ford would be interchangeable? Thanks for your time

Agree with what Ultra said!

HTH, Dave

If you are looking to make your front end heavier the easiest - and probably cheapest way would be to put a front axle from a 3400 on it.
It would use the same power steering system and tin you have now.

The early models did use a manual box with the cylinder in the bolster but it was still reversed due to the way the linkage reversed the direction the wheels turned worked

On the manual steering models the steering link went straight from the box the the left spindle like a 4000 thus operating in the same direction has a 4000 box

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Thanks, good to know. So it's only the later style p/s gear with the internal piston for the 5000 that is reversed? I think that the early style with the external cylinder under the nose used the manual gearbox like the early style 4000 p/s models with the external cylinder on the left side did.

Because of the way the steering is setup in the front bolster the steering box on a 5000 is reversed.

Found that out on my 4500 that has similar steering to a 5000, yoke inside the box was broke so I bolted on a spare 4000 steering box, after I got everything installed I turned the steering wheel to the left and the tires turned right, turned to the right and tires went left, ended up rebuilding the 4500's steering box and swapping it back on.

5000 manual box turns same as 4000.

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The steering box from a standard 3 cylinder 4000 ag chassis model should work also. The radiator mounts may be different on a 5000 bolster as well, but I'm not sure, so you may need to replace the radiator, but as I said I'm not 100% sure on that one. Of course, if the donor 5000 has power steering then you will need to bring all of the power steering components along as well. If the 4000SU also already has power steering, the pump will probably be sufficient at 650 psi, but while the 5000 steering system was designed for an 1100 psi pump, the 4000SU tractor itself weighs less, so I would think that 650 psi should suffice. Also, if the two power steering systems have the different (early vs. late style) pumps, then you will be fabricating new lines.

It will bolt on but you'll need a 5000's steering box and will have to fab a drag link, one for a 5000 would be to long.

You'll also need a 4/5000 front grill shell, SU uses one for a 2/3000 and I'm not sure about the hood fitment.

Once you get it together you have a tractor setting several inches higher in the front than the back unless you install the taller 4/5000 rear tires and wheels.

If your wanting to swap to a heavier front axle find one for a 4000 all purpose, you'll still need to swap all of the components listed above but won't have to fab steering linkage.

4000SU is a pretty desirable tractor, you might be better off selling it and finding a regular 4000 or even upgrading to a 4600.