California car / Surfliner Trucks
The California and Surflinercars have been designed to use Kato high speed trucks part number 800085.  Cut a piece of 1mm [40 thou] styrene sheet to fit into the space, drill a 3mm hole in the styrene sheet and bolt the bogie to the styrene this can now be fitted into the coach. You can fine tune the coupling spacing by moving the styrene in line with the car to achieve the desired position.