Speeds at which shifting must occur

I have grand marquis 97.
Can anyone tell me about the speeds at which shifting of speeds must take place?

Thanks

Depends on how much gas you're giving it. At full throttle, maybe around 40mph to shift to second, then 70-75 for third and if you keep it floored, you might never get o/d. (That's how my 93 would shift) Of course with light acceleration it'll shift more like 12/25/40 or something like that.

Hope this helps

is this manual shifting or automatic? if ur shifting in an automatic then its about 18/to about 35/ to about 60. thats on my 96