Milkypros,
All S-model Preludes for the 4th generation model run used Toyo radiators (OEM p/n
19010-PT0-004), whereas all Si models used Denso radiators (OEM p/n
19010-P14-505). I would play it safe and stick with the Denso radiators but the Toyo unit would probably fit as well.
Hope this clarifies things