up dating my altenator form a 90 amps to a 120?

im looking at up dating my altenator form a 90 amps to a 120 iv got Transporter T25,iv been looking at alternator at 120 amps of cars like the 92-95 vr6 corrado.94-99 jetta glx vr6.95-99 golf gti vr6 (these are the mk3 bodies) 92-97 passat glx vr6.just wonding if it well fit my van and what iv got to do to make it work,or if anyone no were i could get one made be easyer for me.me van a 2.1 wartercool dj vw Transporter T25