the mj was the newer version of the mk with a turbo instead of the multifuel engine of the mk
the tk was civi version and just two wheel drive
if you have a look on the chassis behind the passenger side door you will find the data plate which shows date of manafucture and type
i have pictures on the thread my new bedford of a mk
hope this helps
cost of a engine and gearbox expect to pay same again as truck was