I used 615s and had to do just a little carving to get them in. With Robart 3/8" struts, and cap screw shanks for the connecting shafts, they seem to be fine. I was able to use the well liners that came with it with a little cutting on them as well. You are right though, i think they would be too small for the 73". I'm installing 7/16" struts and 4" tires on my 140 Mustang.