It would be worth paying a visit to the Turbo Technics website. Even if you aren't considering buying something from them, they have a wealth of information on offer.
I've had a look in their online catalogue and it says the following for the Mulltipla:
Multipla JTD 105hp 1999-00 Engine type-182B4.000 Turbo type-GT1544H OEM part no. 46480117
Multipla JTD 110hp 2000-02 Engine type-186A6.000 Turbo type-GT1544S OEM part no. 46756155
Multipla JTD 115hp 2002- Engine type-186A8.000 Turbo type-GT1749V VNT OEM part no. 55191596
That would tend to suggest that you won't be able to use your older turbo on a 2003 JTD. The VNT suffix tells you that the 115hp engine uses a variable geometry turbocharger; it doesn't look like the older ones are. It may work, but won't perform as well as the original unit.