Kev, 103 links is twice the length of what a plunger runs. I'm no expert, just goin' on what I know or has already been stated, in the advertised chain, there's 50 links +con-link =51, or 102 rollers/pins.
5/8" x 102 pins is just over 5 feet.
Seems the difference for 'bike chain' is thinner side plates , as per previously stated, and the Renolds guy volunteered without me asking.
Being thinner side plates makes me wonder if the power/whatever(?) rating is lower, unless they use a different grade of material for these to compensate..??
Call em up, they're at Coopers Plains, I already added the link in my last post as a reference
I have an unused refund in Paypal which will just about cover the eBay chain, so looks a goer for me.
cheers, good luck with it, duTch