Transmission Identification

As my other thread stated I'm having problems with my transmission, so I crawled underneath to find the serial numbers. I'm pretty sure it isn't the stock tranny, either. The numbers I found was JH31 with 68 above it. Can these numbers tell me which Turbo-Hydromatic model I have, also?

Thanks for any help.

Make and model would help more. Can you describe the shape of the pan?