Pick yer poison.
FWIW I have .681 and .658 brand new OEM 5th gears that I import from Germany. Due to the cost of the stinkin' Euro they now run $349, but let me know if you're interested .Cheers,-BB
For trans made before Sept 8, 1987, you do the same as above, adding fluid until it starts to run out of the side 17mm hole, then you plug that hole back up, and add 0.5L more fluid into the trans via the speedo hole in the yellow circle.
Someone said to try a TDI tranny... ButThe TDI is a cable shifting transmission, and the older 1.6 transmissions use rods. Can a TDI transmission be modified for rod shifters? Do the TDI transmissions bolt up to the 1.6 blocks?