It should be a Velvet Drive Borg Warner. Either 1.52 to 1 or 1 to 1 tranny.
is where I got my rebuild kit from. They shipped it here quickly to DFW area. Rebuilt mine in a day. My case seal was leaking right behind my reverse plates. I have rebuilt about 5 of the same trannys that you have and every time I got my parts from them. Good service if you know what kit you want and dont mind not speaking with a person over the phone. It is an internet based supply house. I have also ordered many other parts from them.
The rebuild kit is not expensive less then $350 for everything. If you are handy with tools it is probably something you could tackle yourself on a Sat afternoon.
I would either run on the hose or on the lake and find the leak if it is on the outside or not. If on the hose remove the flange bolts on the back of the tranny to keep the propshaft from spinning and put it in gear forward and reverse. Looking for leaks in a clean bildge and find where the leak is. If you find a leak here it is more than likely a bad case seal. You can also remove the starter and feel inside the bell housing and see if red fluid is in there. That would indicate the front seal is bad, that fix would be less than 25 bucks if done by yourself.
Those trannys are pretty much bullet proof and I could not imagine how it could crack the case.