If you have a complete, working TD engine+ gearbox, it's a straight swap indeed.
It's also possible to fit an Alfa 1,7 TD engine....( it's basicaly a Fiat engine as well....)
The Fiat/Alfa 1,7 Diesel with or without turbo are basically the same engines.
You will run into some minor modifications, as always, but yes ,it's a straight swap.
But you do need engine+ gearbox+ drive shafts.
But don't expect a racing van, after fitting a turbo diesel engine......!!