Tranny Woes

[SVXMAN2001]

Hey guys not sure what's going on with my tranny but i hope we'll be able to get somewhere here. Here's the basic's the tranny has about 30k miles on it since it was installed, it was supposedly a rebuilt unit. These are the symptoms:

1. While driving down the highway at around 50-55 mph I will get a shudder almost like a hiccup, i give it more gas and move up to 60 mph and beyond and there isn't an issue

2. All of a sudden today when i am starting from a standstill and accelerating it won't downshift (very abruptly) till about 3k rpm

3. when i start from a standstill and accelerate very slowly it will downshift at about 2500 rpm.

4. Once i get through the initial gears I am assuming i am in overdrive at this point the car drives fine. Everything is where it should be 60 mph @ 2k rpm 75 mph at 2500 rpm.

So what gives? Is my tranny on its way out? Its too dark out right now to check the fluid level i'll be doing that tomorrow morning. Any help or insight would be greatly appreciated, thanks in advance!

Chris