Have a starter motor problem the flywheel has 104 teeth the starter has 10 teeth and the gearbox is a all syncro with overdrive my problem is the starter has had some modifications to get it to work there seems to be a miss match of something someone has elongated the hole so as the starter can move away from the ring gear and work I’ve put a standard starter without the elongated hole and it jams on the flywheel is there a miss match I’ve bought the car that was stripped and it’s all together this is the issue I’ve had it running with this starter but it’s not right

 

 

It might be worth speaking with these guys: https://www.powerlite-units.com/starters/rac300.html

Your engine looks like one from a later XJ6 which probably explains the mismatch, the one Powerlite list for the 4.2 engine only has 9 teeth whereas the MK2 version has 10 https://www.autosparks.co.uk/powerli...-starter-motor

 

When the 3.8 was in there we had the same problem

 

Is your car manual or auto as the auto starter motor is different to the one you have?

 

In the first thread it tells you it’s a full syhcro with overdrive manual with with 10 tooth starter which is manual

 

I have not had the problem but others have had problems when they mix 3.8 and 4.2 bell housing/starters and flywheels. You must use either the bell housing/flywheel/starter from a 4.2 or the bell housing/flywheel/starter from a 3.8.

it sound like you have a mixed bag of parts and they tried to fix it by slotting one of the starter bolt holes.
cheers
Bob_S