A230 to A833

Swapping my 3spd to a 4spd.. I have the two trannys sitting side by side and I'm noticing some differences.. The 4spd input shaft is maybe a 1/4 inch longer than the 3spd shaft.. Also, the output shaft on the 4spd is a bigger diameter.. I guess I was under the impression that it would be an easy, even swap.. Any thoughts..? Do I have the wrong trans to do the swap.. It's going into a 72 Demon, and the 4spd, I was told came out of a Dart.1108212035a.jpg 1108212035.jpg 1108212031d.jpg 1108212031e.jpg