Comparing the transmissions...
So, if DIY-solution can't be seen as an option I must go with something that were available from the factory in addition that it must be cheap, easily available and reliable. Both factory option I mentioned above were worth of considering, but... The manual unit I have is already high-kilometer one with worn out synchronization, leaking seals and gaskets and at least one terribly whining bearing. Definitely in need of rebuild. Not to mention completely busted clutch and flywheel. As for automatic I had four units which of all four are in unknown condition and perhaps in need of service or rebuild. After brief look over parts availability and prices it became clear that automatic it is. Not only are parts availability much better and prices lower, but (as unbelievable it may sound) they are also much easier to work with. Yes, disassembling/assembling Chrysler torquefligh automatic takes only few hours and you only need few very basic hand tools to get the job done. They are beautiful example of brilliant engineering. Robust and simple.
The 904 it is.
The 727 is an heavy duty version of torqflites with approximately 17% of parasitic loss while the 904 has parasitic loss around 9% making it one of the most efficient automatic transmission the man have ever made. Pretty good for transmission that were engineered in the sixties! 727 is definitely heavy duty and definitely definitely an overkill for Signet's pretty much stock 225 slant six. Also, I have three 904's which gives me good selection of hard parts if I need any during the rebuild and I also have one brand-new non-lockup type converter for spare. So, 904 it is. Without converter lockup for added reliability.
I did not yet pop the pan, but I assume there will be no big damage inside. I guess some new clutch discs and probably front band is what it needs. But more about that in next post! See you:)