The input shaft on a manual box is larger in diameter than the one on a power box. Had to swap couplers with pettybludart (great guy) when he went from power to manual and I went from manual to power steering. The power steering column is also roughly 2 inches shorter than the manual one. If you are swapping from power steering to manual, there is an adapter available from Mancini Racing, Firmfeel, or Flaming River that matches the input shaft sizes and lengthens the power steering column to the proper length. If your coupler is just worn out, there are rebuild kits on eBay for around 10 bucks.