Old chassis/trailer frame - what is it?

This old trailer has been on the family property here in Aus for decades. It originally belonged to another local farmer so we didn't have anything to do with it's construction. I was just wondering if any of you guys could identify the chassis out of interest's sake?

It has eliptical spring mounts front and rear, handbrake brackets and quite a large gearbox crossmember. The rails have probably been cut at one or both ends from what I can tell. I can take more photos if need be.

 

looks like a heavy duty frame modified into a hay trailer. Real common to do. Looks like a more modern frame to me.

 

I'm not sure how modern it could be as it's been there for quite some time. I'll ask again when it arrived on the property. It's sure a heavy bit of gear.