I have a picture of the bottom of a 9918, and without taking the shrink off of my replacement 9920, the components look to be in the same spots. This controller was sent in to be repaired (hence the yellow circles), and was just recently replaced. Here is the only picture I have, of the underside:
SH Z-Car, Custom Crawler, 8s Savage,
12s XTM XLB 1/7 buggy,
4wd 4-link rear/IFS Pro4 truck,
Custom Hyper 10 Short Course,
Belt-Drive Mammoth ST 1/8 truggy, 4s 17.5 MM Pro HPI Blitz