Speedometer Gear Seal

townsend said
In reference to Miller Tool C-4004:
Start seal and retainer ring in adapter, then push them into adapter with a solid 1/2 inch shaft to a depth of exactly 7/16 of a inch. This duplicates what the factory tool does.

You are 100% spot on. Don’t know why this didn’t occur to me before now. I have a 727 transmission from a 66 Coronet that has never been modified. I measured the depth of the c clip. It is 0.453 as shown in the pic - so your 7/16” dimension is correct. Thanks for the verification. This also matches Dana’s pics from an earlier post.