[Graham]

Sorry, It's an 'M construction' not 'P' (what was I thinking! )

The chassis I have doesn't have a separate motor pod, the motor is just fixed to the chassis so there will be a hole in front of the motor if a short motor is used instead of a long motor.

So nothing standard will be substituted as it'll be fresh air.

I think you need to show me a photo of how the adaptor with the motor fits into the chassis, and how you want to fit the ballast into it as I am not very familiar with these adaptors.