The crossover was slightly upgraded on the 3.6s but i do not know the year. My new in 2010 3.6s have a larger crossover box the connects and sits vertically. The older box was smaller and connected horizontally.
The Glue for the wires/panels was changed like five years ago or so, and the story is the newer ones will never delaminate.
the older ones can be refurbished by Magnepan, and at the Magnepan boards, folks are regluing them and it is not a big deal, certainly not a speaker killer sort of problem.
The outer socks are also replaceable.
The basic 3.6 has been around for 15 years.
And old ones are just as musical as new ones.
The delaminating is sort of the Magnepan equivalent of needing new foam surrounds on woofers IMO.
Magnepan has always held great on used prices, and buying them now, the price will not drop again for a lot of years.
The one issue is shipping.
I almost had a chance to buy a used pair close enough to pick up. but the money right at that moment fell through for me. So i suggest watching for a pair close enough to go pick up. The panels are large and bulky, so shipping is expensive, and fraught with problems, though new ones never have shipping problems. Any van can be used to carry them.