I think my tranny is toast.

You sure that isn't a reverse manual vavle body?

D would be 1st gear

S would be 2nd gear

L would be 3rd gear

But you say 1st gear is in both D and L ?

Why not start in D and get on it kind of hard..2/3 the gas and shift at 5,000+ and run though the gears...you know for sure at 70+mph shifting in to L if that is 1st gear or 3rd gear, lol