Chainsaw Repair

Thanks for the links everyone. I was able to leverage my local store down to a reasonable price on an 18" powermatch bar. This way I don't have to deal with shipping or exchange rate. Now just need to settle on chain. I'd like to stay away from the safety chains, and a lot of the firewood I cut is dirty dead-fall so I'm thinking semi-chisel is my best bet. I found a nice semi-chisel by oregon (DPX) so I think I will order that to try. My Stihl dealer tells me they won't sell any chain other than the green stuff, so much for trying out Stihl RM. Do I have to order the chain based on the exact drive link count specified by the bar (in this case 66)?