Alright, as the title says I have a 66 RV (w/o ETA and 160mm). I also have a marz AM1 (w/eta and also 160mm). I want to put the ETA cartridge into the 66. I dont see it being a problem because there the same size and marz also put out a 66 rv w/eta that year. Ive worked on bikes but never really messed with suspension more than changing oil; so I would like a little info before I start tearing stuff apart. Thanks for your help ahead of time.