hook your tape on the outside of the flange & measure out to where it starts to taper, if you have at least 28" you're good. I think it's $110 for the housing & $110 for the axles & $55 for the perches(plus new perches) plus the shipping to Portland Indiana & back. Be sure & tell them to relocate the perches on the other side of the(truck) housing(I forgot to do that & they didn't catch it either ) & they will relocate them at 43.125" & factory was 43.02". that amt I wouldn't think it'd be a problem but I wanted mine factory perfect so I gave them that dimention rather than telling them "to A body dimentions" .