The banana boxs are different between the 411 and the 406, but theyre the same on the 411 and 421. the banana boxs do swap over but the 406 is physically bigger. also on the early 411's banana boxs werent fitted, but yours should be ok being a '65. theyre fitted by a bracket on the back, the proper thing is quick release, but you can make your own bracket. if i have the time i'll take a picture of our 406 one tommorrow, and the bracket. the 411 one isnt on at the mo as its seals are kaput.