1988 Code E059. ? Transmission Sensor

HELP. I just bought this 1988 caddy deville, and the engine is great but after the car gets going and is hot, the service soon light comes on. i did a self diagnostic as described in a manuel, and the code E059 CAME UP. i looked it up and it said transmission input speed sensor. does this mean my tranny is dying? is it something that will warrent a complete tranny overhaul. i dont have 1200.00 for this and am pretty upset. although the car only cost me 500.00. is this something that can be reached w/out lowering the engine? any help would be greatly appreciated. and is this the correct code. it said EO59 WHEN I WAS CLEARING THE CODES MYSELF. THATS THE ONLY NUMBER THAT CAME UP.. thanks everyone.

Welcome to AF. Go to caddyinfo.com for full code info.

The input speed sensor doesn't mean the car is dying. It's probably just a bad sensor. But how does the rest of the transmission run? It probably shifts a bit hard now, correct? That's due to the input sensor. How is the fluid, is it very dark and burnt? That would be a sign of a transmission on it's way out.
I'm pretty sure that the input speed sensor can be changed without dropping the transmission. I think it can be accessed through the drivers side wheel well. It's a bit of work to change, but not impossible.