1930 Blower Bentley 1/12th scale

[Factman]

Just got the latest version of the1/12th scale 1930 4.5ltr Blower Bentley. Going slowly and carefully since I have not done anything like this for almost 70years. First problem was missing part 55 for the supercharger, but Hornby team came through and mailed a replacement. Now at the point where I connect the transmission to the prop shaft to the rear differential. Part 106 is supposed to couple the back end of the prop shaft to the rear differential, BUT IT DOES NOT FIT. The square key at the end of the shaft is larger than the key way on the coupler. The back of the coupler has a larger key way, but nothing connects to it. Is this part a hold over from an earlier kit version? I can drill and cut it, but will I regret that move?