David:
I don't have the lengths for your 42DC. I replaced both throttle and shift cables on my 36DC. If you look at the cables, there should be numbers embossed. Those number reflect the model and length. My cables were Morse, which morphed into Teleflex, then Seastar and now Dometec. As far as cost, once you have the model number, run it on the internet and compare prices.
Gene