I used ACE transmission here in Loveland for my 4r100 rebuild. Was right at 4k if I remember correctly. You could also get a transmission from Ford. I know they have a HD version now. Also Zach's Transmission in Longmont was recommended to me from another forum. Lots of options out there all about how much you want to spend. My transmission still runs like a top...no complaints on my end. My EX is chipped and generally always in the high setting.