They dont retool all that much. Plastics and panels, mainly. The Tesla approach is materially different in pretty substantial ways. Using the battery as a st

They dont retool all that much. Plastics and panels, mainly. The Tesla approach is materially different in pretty substantial ways. Using the battery as a structural member means that before its glued in the frame must be handled more delicately. The drive unit mounts are totally different and potentially require almost the whole suspension to retool conpared to normal. The little differences can have huge impacts: Tesla batteries are just a few inches wider than the Bolt's, but those few inches mean wiring has to go through the roof or side rails instead of a more conventional route. That's a really seriously large change for some cars. They potentially have to run wiring before the interior, drive or battery goes in- completely changing the factory floor.