Replacing part like this in an automatic transmission is not something that most people will be doing in their garage on a weekend. Automatic transmissions do not come apart and go back together easily. There are many special tools required and more in depth knowledge is required. By the very nature of how they are put together, taking one apart means you will be doing an overhaul. There are seals, bushings and gaskets that must be replaced and ones that you would be foolish not to if you have the transmission dissassembled. You state you are worried about a repeat failure if you use a factory replacement part, by that logic you should be also considering doing the full overhaul so you dont have an old seal, or worn clutch pack fail shortly after making a repair. Check out some of the local and on line rebuilders and see what kind of pricing you can get. Compare that to the cost of a master rebuild kit, other broken parts, and the extra time and effort, not to mention no warranty of any kind. You may find a logical arguement to just install a reman unit.
