take a small hammer
check , rear xmember - esp where the chassis rails mount to it , front outriggers , on top of the chassis along the main rails ,
and everything behind the rear axles - tap it all , ringing = good , thud = bad.
check the door bottoms on all three doors
seat box ends
check the bulkhead inside and out and from under the bonnet , remove any mats/carpets and look , pull back the door seal at the bulkhead and check for rot under the window./hinge mount
check for play in the diffs , jack up each of the wheels and check for play in all directions inc rotational.
check hi/lo and lock all work and dont pop out.
drive through the rev range in all gears and use overrun coming down - particularly in 2nd.
check it doesnt wander under power , or braking
do a check on the plates too , check its not a ringer , worth doing a history check on the reg plate too
and youll do all that and still buy a stinker
where are you located - might be a member localish to provide an unbiased realist view ?