Speedometer inner cable to short...Model A

[GreatLakes28]

Bought a complete speedo cable, it broke. After purchasing an inner only, rebuilding the speedo head the replacement cable keeps sliding out of the head because the screw in is totally different. There is to much space from the cable boss to where the cable meets the retension part of the outer cable. I modified mine with a spacer. Has anyone had the same issue and what did you do to correct the problem?