Spacers not necessary for Prometheus. Motors are longer than those in my Prometheus but there’s juuust enough clearance for them to fit.
Not one to normally leave less then 5 stars... especially for this incredible shop! However, these motors burnt up and I finally gave up trying to replace my nemesis motors with them after burning through 3 of them. I used the recommended spacer too. This is not a complaint, but should be considered before being used to replace nemesis motors. All part of learning and modding.