I hear that they are all inter-changeable... Some do require minor filing on the bolt holes though.
Why would you want the Older (larger) type of engine guard on a newer wing? Reason I ask is that I hated the ones on my 1990 so much that I took a hack-saw to them and reduced them roughly to the size of the later style... The large ones are a problem if you use hwy pegs, in that they interfere with your legs reaching the pegs... very uncomfortable!
Why? I have nice hiway pegs that fit the older engine guard, and for the life of me I can't see room to mount hiway pegs on the newer engine guards. But maybe I'm just not creative enough.... Thanks for all the responses.