While there was a 70 series "Prado" sold in some countries, it was never sold as a "Prado" in Australia (This forum is Australian based and covers the 90 to 150 series Prados only, although we do have some OS members)
The closest model sold in Australia was the 70 series mid wheel base "Bundera" in around the mid/late 1980's.
The Toyota Landcruiser Owners Club in the UK. and the IH8MUD forum in the US have 70 series sections within them and might be some other good places to get some info on your 4wd when it comes to suspension etc.
Comment