They can just do what they did on the 6 before the full conversion of the Kawasaki R142A which was they ran all the redbirds to Pelham Bay Park & all the R62's last stops were set for 3rd Av - 138th Street & Parkchester, But if I had an opinion on where the R62's should go I would say it should go on a line that faces little or no destination sign changes or platform construction work & before placing the R62's on any line the announcements need to be modified to be loud & clear not no loud electrical buzzing sound then the piano but the r62's could work on any line as long as they keep the countdown timers working cause those really tell u where the train is going if the sign isnt being updated