Trans speedo adapter for 69 yenko camaro

[enio45]

I also understand that the speedo adapter was used for hipo cars with 4:10 gears but with 14 inch tires (like copo cars and L78 cars. If you had 15 inch tires then you did not have a need for the gear reducer. Makes sense from the point that i have not seen any 69Z with 4:10 have the reducer (which they have 15in YH's).

Not sure the correct application as of yet, but maybe others can chime in. Would the parts book show a specific application?