Differences between magnepan MG20, 20R, 20.1

I have a pr. of MG20's. I would like to know what the differences in the models was. Actual re-designs of the 20 for the "R" model and 20.1 or just x-over refinements. Will the passive x-over from the 29.1 work with the MG20??
Thanks Scot
I believe I have my facts right,Sscot1961,so here is the information you are looking for. 1)The difference between the MG-20 and a MG-20r was not a structural change in the panels but revolved around an upgrade of the passive x-over.2)The difference between the MG-20r and the MG-20.1 was mainly adding magnets not only to both sides of the woofer panel,as is found in the both the 20 and 20r,but putting magnets on both sides of the midrange panels.3)I do not believe that you can use the x-over from a 20.1 with a 20 because there are different settings because of the change in the panels.I have MG20r and always found that they sounded much better bi-amped,I use a Bryston active x-over,than when using there own passive x-overs.I did a comparsion between the 20r and the 20.1. The 20.1 were subtly better than the 20r,but I thought I could use my $ resources to get greater improvements by up-grading my amp and digital front end. But I strongly believe,based on my audtioning process,that all the 20s sound much better when bi-amped.
There was never a 20R only the 20 and 20.1.