Turning a fully floating axle into a trailer axle

I know many people just gut the differential and call it a day on these. It works, bit I think it looks ghetto, takes up space under the trailer, and adds weight.

The axles in my Disco are fully floating, after watching a video on shortening an axle, I had the brilliant idea of cutting out the middle of the axle all together and just welding in a section of adequately sized pipe, adding a drain plug to add a bit of oil to keep the bearings lubed, and bolting the whole thing under a trailer using the Disco's stock suspension.

I had thought of doing this to use up spare parts (an axle and rims) and to cut down on the number of spare tires I would need to carry.  The thought of also having a perfectly offroad capable trailer behind my disco is tempting too.

So, regardless of the price to do it.  Would cutting out the "pumpkin" and welding in a straight pipe work?

Price a new axle and see if you are willing to take it on.  A axle like yours would probably be a 5000lb axle, which are not horribly expensive. And have proper brakes. 
 

And don't forget the trailer tires. 

Since the full floater has its own inner and outer bearings, I think you'll be fine.  I would cut the axle shafts off and just keep the flange so you can seal up the outside.

If you're looking for additional clearance, you can ditch the center and replace with a slip-over tube, or you could just leave it in place and deal with the weight.

I would do drain plugs on both ends.  Waiting for it to drain in the middle might take 1.5 decades, and the chances of the axle being perfectly level are slim.  That way you can drain it anywhere you are, just pull the lowest plug.

The center housing alone isn't worth much money unless you find that ultra rare person who is looking for one to custom build.  The diff might have some value, especially if its LSD.

Depending on if it's a disc or drum, you could machine off the drum/disc and leave just the bearing hub.  Then you could ditch the backing plate.  I suppose with a lot of maths you could also maybe cobble together a surge brake setup for it and leave the brakes in place.

Edit... caveat that I have never played with a Disco full floater, but it should be a do-able thing

The slip over tube was what I was looking for.  I wanted to cut out the entire centre of the axle and have a tube welded into place of it (I do not trust me own welding for this).  The idea of two drain plugs is a good idea, thank you!

No reason a strait chunk of tube to be the cross beam wouldn't work.

Also why wouldn't you just cap the tube ends before welding so that you keep oil on either side at the bearings instead of in the middle. Could possibly modify the end caps to have a sight/fill for the oil too.

Bridging the gap left in the absence of a trunnion seems like a perfectly acceptable solution to me, but I think it's very likely to be less work and less net cost to sell the spare axle and simply redrill the hubs on a trailer axle to match your disco if you so desire. I am not sure if there is an inexpensive way to actuate the Disco brakes with an electric over hydrailic actuator or if it is a smart idea to fashion a servo to manipulate the park brake cables (also is this a drum or disc brake? If disc, using the park brake as a trailer service brake is a really bad idea).

The parking brake on Discos is a drum that actuates on the driveshaft by the transfer case, nothing in the service brakes themselves. 

Smart move, the overland crowd likes this kind of setup because this way your trailer spares are also vehicle spares and the resulting trailer tends to be more off-road-capable.