[wheelbender6]

Sounds like you were working on the 53A, Irish.
Sikorsky later added external tanks to the stub wings for the 53D or delta.
In the 1980s, the 53E entered the fleet. It had 3 engines.
53E pilots called the previous versions of the 53, "Light Twins".
We shared a hangar with a 53E squadron when I was in the USMC. It was a real beast.
You could drive a HUMV right up the ramp and into the cargo bay.