PETER - Best shot at Mulching blades for Your 48" deck is to measure each blade for length, width, thickness, and mounting hole diameter and do a search on "GATOR BLADES" and see if they offer anything that fits. I'm not familar with the various 48" decks to know if they all have three identicle blades on them like the 44" & 50" decks. I know Gator doesn't make blades to fit the 38" & 42" 3-blade decks because the center blades are one length and the outer blades are a shorter but same length for each size deck. I'm not sure if they make a blade for the timed 38" two-blade decks.
An e-mail to some of the sponsors identified by the colorful boxes above this forum would get You availability, price, and delivery info I'm sure.