I tore down my 39 trans to rebuild for my 26 t coupe build & have something throwing me off . It has a 39 serial , double detent tower , 78 case & has the 28 tooth gear . But it has the small 2 3/4 fork ? I always thought the double detent had the 3” forthe later gear set? The fork just has a square box with a c inside it & the number 52 beside it instead the the ford numbers . Anyone seen this before or was this common ?