[RICK LAKE]

Scotchman Here the thing, T-5 is not a super strong trans to start. With this many miles and years on it, I would recommend a Fluid check and sample of the fluid.
Here's how to do it, Get a glass jar and loosen the bottom plug. Get a sample into the jar. Check and seen if there is a mushroom on the bottom plug of metal or partials. If there is alot, change the fluid. Listen for any noisy or shifting problems. I believe it's the 1-2 or 2-3 shift that starts to give you problems in these trans. Binding, grinding, forcing, The shift is not smooth anymore. If the fluid looks good after it settles for a while, just top it off and keep driving.
If we find metal, black color of the fluid, we may be starting to have a problem. I would recommend change the fluid and enjoy the rest of the summer. I would look into a tko500 or tko 600 trans for the car and not put $500.00- $1,000.00 for a rebuild. This a bolt in with the same parts on the motor. Just need to check the clutch out.
You didn't say about how much power your motor puts out? Looking at torque numbers more than HP. If we are getting into the 500+ of HP would go with the TKO-600. It's strong and will take alot more abuse.
I run Richmond and G-Force trans. They are built for alot of abuse, and not cheap either. Good luck with the car. Rick L. Ps keep a watch on the trans for leaks after the fluid is changed or topped off. I don't have the answer but when adding new fluids to a motor, trans, rearend, you start to get a leak or seep from a seal or gasket. Cardboard under the car works the best for checking. Rick