DC5's have a defect in the 6-speed gearbox where the shift into 2 or 3rd gear is crunchy. The TSB in the US is to change the synchros, if I remember correctly.

MTF06 has the same part number as the MTF plus, but it comes from a different supplier (Australia instead of USA). I suspect that the place contracted to manufacture MTF06 uses a formulation closer to Redline since it did mask/fix my tranny grinding issue. Also, it is a different colour (grey instead of gold).