The 69-70 Commando (Including S) Parts book and Workshop manual, that I have, don't include any exploded views of either the rear lamp or stop light.
My Haynes Commando manual 68-77 doesn't contain any either.
Here are the part numbers:
REAR LAMP------Description-------------------Qty
24840------------Rear lamp (Lucas 679)-------1
54577109--------Lens-Red-----------------------1
572289-----------Lens screw--------------------2
54571677--------Lens seating gasket----------1
54574348--------Bulb holder with reflector--1
380---------------Bulb----------------------------1
6.0909-----------Rear lamp screw-------------2
6.081------------Rear lamp lead---------------1
STOP LIGHT-----Description------------------------Qty
31621------------Stop light switch-------------------1
6.0677-----------Stop light switch screw-----------2
39----------------Stop light switch screw washer--2
6.0678-----------Stop light switch screw nut------2
6.081------------Stop light switch cable------------1
6.0693-----------Stop light switch lead bracket---1
Don't know if that's of any help, or you already had that info.