Replacing LU70 High Pressure Sodium Bulb with LED?
Funny, I just replaced one of these last week for the first time.  Both the counter guy at the electrical supply counter and the bulb manufacturer ( paperwork in the package  of a high output LED bulb with the same "A" type screw base) gave the same instructions. 

"By-pass the transformer and all associated hardware and wire the socket direct".  While you can just screw in the new bulb, it is not designed for a transformer and ballast(?) that the lu70  needs.   Easy job, I just didn't know there was even a transformer in the housing.   I would have probably ruined the $55 replacement LED if I hadn't listened to the pros.