Re: t-150 leaking
I had the same problem with mine. I had just bought the Jeep, checked the fluid and all was OK. 30 days later the tranny froze up from being low on fluid. It turned out that the bolts that hold the top cover on were not tight and some were missing. The bolts go through the top flange of the case so if they are missing or loose, the fluid leaks out as the gears spin. After the rebuild, I used Super RV sealent on the gasket and also dabbed some on the bolts before putting it in the hole. It worked. You could also use some teflon "pipe thread" tape on the threads to the cap that hold the shifter in place to stop any fluid from escaping from there.
Hope that helps!