At the dawn of full suspension bikes, there were many different designs that were tried since, unlike today, there were very few off-the-shelf parts to choose from.  IRD went with an elastomer stack that was attached to a braided cable that wrapped around the bottom bracket shell.  It is a pretty ingenious use of the existing frame but I wonder about the longevity of the thin wall frame tubes with a braided cable wearing into the tubing.  You can see that the cables have already worn shallow grooves into the frame tubing.   Ray Baldwin and Rod Moses applied for a patent on the swing arm in November of 1991.  From the IRD catalog:

 " Adjustment is accomplished by elastomer durometer and threaded ends of the cable which terminate in the swing arm cavity.  By tightening the cable ends several interesting things happen.  The chain stay dimension shortens, the bottom bracket raises, and the head angle gets steeper.  Of course, the opposite happens when the cable in lengthened, permitting you to fine tune the handling to your own preference." 

Overall, a very neat effort but I would guess that relatively few were produced.  This particular bike would be much more "complete" with an IRD seat post, suspension fork, seat quick release, stem and Widget brake.  If I can find these parts, I will replace the parts that are currently shown on the frame so let me know if you have anything to fit the bike.