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28 Posts
The FS5R50B is what is on my identification plate and is a factory TD42TIf that is a typo and the second box is a FS5R30B then that is not the box to choose, that is the RD28 box I believe.
Did they ever sell the TB48 in AUS with a manual trans? I just assumed they were all auto's...50A is the GQ box, 50B is the GU box.
You ratios listed for a weird number below that which has 9 in there that i assumed was a typo and should be 30B that is the 2.8 and possibly the RB30 box.
50A is single synchro the 50B is double synchro. Basicaaly the same box, selector fork grooves are different width between them, different selector setups and totally different top of the box fitted to them, unfortunately you cannot just swap the tops of the boxes over.
Internals can be swapped between them but selector rings need swapping because of the groove width.
But strength from my perspective will come down to which version of the 50B box you have, 4 versions available, they have different input shaft teeth counts between them, this affect torque multiplication I believe through the box.
The version of the 50B you have listed above is TD42T coil cab DX and ST and the 3LT from memory, these are the ones I have broken the most of.
The leafy boxes with the lower first gear and the .83 over drive have different input shaft tooth counts, same as GQ infact, and as are the ratios, and these seem to hang on a bit better with some power.
I have a brand new TB48 box in my ute now, which is terrible with its .88 overdrive, all other gear ratios are fine, never had one apart to count things however to see what makes it tick.