First of all there aren't many models available out there.

There are two kits available in model shops currently. Tamiya 1/35 scale and Airfix 1/72 scale. Both kits represent first marks of Chieftains and contain multiple errors.

I have also seen pictures of a 1/25 scale Toycraft model somewhere on the Internet but it looked more like a toy than a real model.

Tamiya kit was released in early 70-ties. Various resin conversions are available from Accurate Armour. The only parts saved from the Tamiya kit are the lower hull, suspension units, wheels and tracks.

The AA conversion is quite detailed and with some effort you can create a decent 1/35 Chieftain. It is however very expensive and still requires some upgrading. Having built one myself, I don't think it represents good value for money.

Quite recently I have been sent these photographs of this 25th anniversary Tamiya Chieftain Prototype model. Many thanks to Ross in Texas, US for guiding me to this model.