Help needed with selecting the right motors

[KAF1]

Good day to all, in have 3 Tamiya Semi trucks building. One is a tractor (Aeromax), one is I have a flatbed kits from PMD for (Knight Hauler), and the last one is will have on a screw driven dump box, which I don't have as yet is going on my King Hauler that has on 26" frame rails. I have been watching RC4WD 45T,55T, and 80T motors. I have had a Knight Hauler in the pass and know with the stock motors from Tamiya, it goes faster that I would like. Any suggestions on choice of motors for these trucks. I will be use the Tamiya 3 Speed Transmissions that are supplied with the kits. Also, what ESC is recommended to be used with suggested motors. I do plan to load these truck up with dirt and materials, so please keep that in mind. Thanks in advance for any help you can give me.
Kenneth