Wiper bushing help

I'm trying to rebuild my wipers. I have dorman wiper linkage bushing # 49447. It list as being for a 74-2007 chrysler products. I however have a 70 dart swinger. They go on just like some of the threads I've read, but they just fall off when you move the wiper arm. Where can I get the correct bushings. One post said dorman 49440 but that crosses over to a NAPA 665-1537 which is exactly the same wrong bushing. Any help would be greatly appreciated.