I think my Caprice is leaking transmission fluid, but the dipstick still says it's full. Overfull actually...

Just check it after you go for a drive.
Or, if it's not moving, maybe idle for 10 minutes in drive or neutral, just so you can get the fluid warmed up and expanded.
On 99% of vehicles, checking auto trans fluid is done this way, as operating temp is reached after a couple minutes worth of driving

I changed the filter over a year ago, and have driven less than 50 miles since then.

Your transmission is fucked. The good news is that turbo 350's are dirt cheap.

fucking hell lads

You got the 305? If so it might be your rear main seals, I had the same issue on my old G body Monte Carlo w/305

Yep

There is literally nothing wrong with that

>B-but muh euro shitbox has tighter gaps!
>A-American quality is shit

I know right. If you ask me I'd say that artist's rendition has been wrecked, maybe totalled.

Might be a blockage in the cooler lines, take them off and run something through them to check.

Could also be leaking seals, you could try dumping a bottle of lucas transmission fix through it and see if it helps.

If your radiator is rusted out you could have coolant in the lines, which would destroy the clutch pack material and other stuff if it had a chance to circulate.

It might just be low on fluid,in 70s slushboxes the valve body and lines can suck up and hold a lot of fluid once the engines going and can leave the pan low which can lead to erratic dipstick readings.
Let it get warm and then try doing a reading.

gasket from the pan is worn. Replace the filter and gasket.