I'm sure the spindle only comes into play when refering to the 6 rib 091 box as on the 2ltr motor the i/p shaft sits deeper also the bell is deeper, o the 1700 box I think its basically a 1 for 1, I've not looked into it as the 1700 was such a short lived motor..... EDIT - having a look through a few docs is it not the same box as a 1600 72 being an option year CE box