The square plug looks like an adjustment for end play. This may be able to solve your 1/8 inch play.
The unit looks like it is a reducer and may not be correct for the mark II.
It's been a long time since I have looked at the transmission connection on my car but I'm not sure this unit is correct for our cars.
Lets see what other comments come in.
Jack Bowser
C56B2198
Past Ownership 1991, 3206, and 1763
2006 Ford GT
2006 Cadillac XLR-V
427 Cobra
2012 Mercedes SLS AMG Roadster
1924 Dodge Brothers Rat Rod
Lots of Bowser gas Pumps