Bon Jour, Frenchie
If you have an enclosed drive-shaft, you most likely have the original 1954 1/2 ton 3.90 ratio rear end.
You could convert to a 3.55 rear end.
SWEET wrote an excellent Tech Tip for this.You might want to buy the Ring & Pinion from
Mother.Trucker (a member of this discussion board) and buy an
installation kit from Classic Parts (or others).
You also will need to buy a used ring-gear carrier (used in earlier 1/2 ton 4.11 rear ends).
If you want to calculate your "effective final ratio" - other members will post explanations.
I often use the calculator at the bottom of this page.
