The author remixed this model.
I modified the slot to increase it by about 4mm. This accommodates the larger Fastback that I have. I'm not sure how many there are by my slot is about 20mm deep vs the original which was 16. My fastback was around 19mm deep. (Deep in this case refers to the size between the sides of the fastback). I really appreciate Austin including a Step file to make modding this easier.
Edit: I added a reinforced version that makes the blade guard less flimsy. Mine broke off – the reinforced version should help with that.