Your truck
https://www.hpiracing.com/en/kit/10511
Super nitro rs4
https://www.hpiracing.com/en/kit/484
Hpi has a standard parts tab that lists parts for your cars.
The only way I see starting is is to disconnect the muffler. If you do, wear hearing protection. I personally wouldnt.
You may...
Welcome to the site. Hpi rs4 belt drive? If
It is, those parts are harder to get then the shaft version.
I would go this route, if they have it for your motor, I'm assuming is a 15fe.
https://sullivanproducts.com/sullivan-products-tiger-drive/
You can also go pull start. I've used hpi roto...