TANK SLAPPING! steering Mania

Help!
i have spent 2 days removing a huge hydraulic winch off an early series 3 with parabolic springs and 235/85 BFG tyres.
the lady owner reports mad side to side steering slap on moving off at a right or left lock. She has smashed her elbow and i have seen the bruises.
What on earth is the cause of this? It is reported as a bit like tank slapping on a bike...
the winch and tank probably put 150/200kg on the front end as a load which is now not there.
ideas?

jamming/ sticky front axle UJs? or a mad spring in the steering box. Has it got FWH?

Could it have had uprated springs on the front for the winch, causing all the steering rods to be too short?

The extra weight might have caused/covered up wear in the swivels - the preloading on the Railko bushes is supposed to generate some steering damping, but it's a complicated steering system with lots of opportunity for wear - slackness can cause osciillation.

This is a common problem on series landys known as the "Death wobble" and the only way to stop it when it starts is to come to a complete standstill.
You need to check all the steering components for wear but it will probably need the bearings and bush in the swivels seeing to.

thanks Guys, i will go and have a look tomorrow.
would a steering damper help? i had a less serious problem 6 years ago, fitted a damper and , well it made no difference!
thanks again.
the winch is on Fleabay now.

oh and another point, it has parabolic springs and no FWH.
i also have no FWH 'cos the chap i bought them off on flebay still hasn't delivered them.
Steve; send me my hubs you wazzock!