The towing placard on that vintage wagon should be on the inside edge of your rear barn doors mate. From memory only the TD42 (manual) & TB48 are rated for a full 3.5T towing capacity. All others are much lesser and the placard also explains max legal ball weight too I think for different variants. As PeeBee kindly mentions GCM above your GVM and axle weights is the killer for most Patrols & Landcruisers bums too! Patrol rear spring coil towers absolutely must have aftermarket braces put on top too mate and kevlar bagged poly air bags will be needed for added ball weight ride leveling.
EDIT: Here’s our old girls placard picture.
(2001 TD42T)
Sent from my iPhone using Tapatalk