I´m pretty sure Toby wants a D36 dropin. Of course it doesn´t just drop in that easy compared to the tower modules since you´ll have to pop open the bezel and insert it from the front
Are you planning on using the shock absorbing foam in your build? You can cut down the old reflector and use the end portion as a retainer. At least that's what I used to do. Now I just make my D36 dropin's longer and they are held against the plastic front foam retainer by the force of the outer spring.