I think my shafts are a tad short for my horse… where does one find longer marathon shafts to fit a pacific carriage? It is not a dartmoor… not sure what it is but smaller version.
My current shafts measure around 60 inches and my friends are 66 inches on her carriage. Hers is not a PACIFIC.
Not sure this will work for you, but Facebook has a lot of groups selling carriages, pieces/parts of vehicles. You could join a few groups to ask if anyone would sell you longer shafts. Post an ISO (in search of) request on the groups, along with your general location. Shipping cost might be a consideration going from one coast to the other.
Martin’s Carriage Auction is this Friday at the Lancaster Fairgrounds in Pennsylvania. There could be shafts consigned in the misc. room, which you could bid on. One never knows what will turn up at the Auction, both cataloged and misc. consigments. Amazing finds, maybe at bargin prices! But you have to attend to sort thru things and bid. I suggest arriving late Thursday or early Friday before selling starts, to have time to take everything in.
Pacific Carriages are no longer being made. Perhaps you could take your short shafts to a local welding or metal fabrication shop for evaluation. They might be able to make a longer pair for you at a reasonable price.