For a T3 conversion you will need

Obviously a T3,
Escort turbo down pipe and manifold,
Escort turbo oil feed pipes,
You may need to move the rad forward but we just ground the actuator bracket back a bit
And a few boost hoses need to be modified slightly

its the best modification to a frst, its so worthwhile in the long run and as budweis said, its a lot cheaper than a T2 by far