Ick. Check fluid level. Find the vent for the transmission, dipstick or plug on top. Use a straw or wire like a dipstick. Add fluid if necessary.
If it is the same transmission as in the link below, they are easily rebuilt by DIY. I posted an informative site in the link below.
Another option is to install used. Ebay, Craigslist.
Hydros are great when they work but expensive to replace when they break.
I replaced a mid 80s hydro pump from ebay. Shipping was the expensive part! It worked for about a week. I let it sit for over a year. I decided to fire it up but trans was bone dry. Instead of using hydro fluid in it, I put 30 wt oil in it. Why not? It was already broken. Has been working great since. Even replaced the output seal.