Starting in 1990 they put the P3 rotor system in the R60 and 70s. The R40 and 50s had been using the P3 in a shorter vertion for about three years allready. For- aft cage sweep was introduced that same year for the larger machines. That is the main things that was different between the prior and eff R60-70s. Can't go by the orange strip to much in our area because we painted alot of the green strips orange. Take care