MAG20 lower tubes look different

the top part of the lower tube will be more angular, as will the bottom part. (main thing to look for)
plus they should have a angular style (sharp edged) crown, this could be changed though
For brace with recessed bolts, slightly more 'tubey', could be changed
(P.S. if you are lucky and the serial is still on there 'Forks with serial numbers 27266 through 158841 are involved in this recall' are MAG20's or 30's, though I don't think that is all of them)
MAG21 '93
Same brace as the MAG20, but the crown will be smoother with a sort of 'ring style' just above where the stantion goes into it.
Fork brace with 2 holes under the canti hanger for reflectors, but these can be changed for newer ones, fork could be changed though
lower tubes smoother <- main thing to look for and only real give away
MAG21 '94
Different smoothed and more milled than '93 also the 'ring' styling has gone.
Different dial, they are a chunky machined CNC types rather than a thin dial type.
Brace changed, only one hole for the reflector and 1 position for the canti springs.
Alu (gold) stantion tubes (so this one is really easy)
Internals are different now for improved riding.
MAG21 '95
Loose track but I think back to steel stantion tubes, else pretty much the same
MAG21 '96 to '98
Same, but they may have brought in the all in one colour and brace here. (could have been '95 they did that)