Hi there, and welcome to the club..

The RF diesel engine was fitted to the 1988-1992 "GD" 626's
I have no idea on numbers, but would imagine very few were sold back then..
There was a later "GE" 626 called the comprex, with a supercharged diesel
engine, again only a few were sold... I can only presume it is a completely
different engine to the RF.

John