Leaf springs on 09 pre runner

My 09 pre runner v6 access cab has 170000 miles on it . It was my dads and he give to me before he passed away . Everything on the suspension is original from the day it was new . It has never been abused which is why all this stuff has lasted this long . But it’s time for suspension stuff now . I am going though the coil over deal now on the front but I read a thread that said the rear leafs might be nearing their end . Is this something I will need to look into ? The new 4600 coil overs are supposed to be a stock height but I expect some lift because mine are so old . But I damn sure don’t want the squatted look on my truck . Any info will be appreciated .