45" speedo inner cable difference question

[BigLakeBob]

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Putting together speedo cables for a '41 and up style trans for a solo and a servi car. I have the correct length outer cables to match the correct year speedometers I have for each different model. But, I have 2 inner cables of different diameters and ends for both the different lengths I need. Can someone tell me why there is a difference? The cables on the left measure .125 diameter and have a single collar, the cables on the right measure .150 in diameter and have a collar on both ends. The square ends that go into the drive and speedo housings are the same on all the cables, about .100. Thanks.

[Rubone]

One type is for the large housing, one for the small. Double collar for large.

[BigLakeBob]

Thanks Robbie, that makes sense. But confusing on the 45" HD solo. According to Bruce the outer housing diameter changed in '57 to the smaller size. How could I have a solo smaller inner size since they ended in '52. New replacement stock made after '52? I appreciate the info and I'm using the larger 7/16" diameter outers so I'll use the .150 inners. Thanks again.