I would think the longer length would be from a truck (4X4) or van, due to the action at the rear end while carrying cargo or 4-wheeling. That way the slip yoke could compromise the inner and outer movement. Fitting into the transmission should all be the same. I would think the longer would be best for a HI-PRO car for the same reason. A frontal separation of the driveshaft is not good. All of mine are long.