Sonido Mask 2000.1 end-FETs

[tobi320i]

I am working on an sonido mask 2000.1 amp. it is similar to the Sinus Live SLA1500.
Can i use the irf 640N fets instead of the original utc 640 fets?
I have them in stock so there would be no need to buy the original utc 640.

 

[Perry Babin]

These amps (SLA1500 type) have used both the N-version and the non-N versions.