This ^^^ is the main thing. It's really not an end al be all so don't let it worry you. @Charrlie_S may still have some adapter rings. It just slips in the rear crank register and adapts the smaller converter hub just like @MOPAROFFICIAL described. Nothin to it. Also, you need to make sure your oil pan is the same. They are all interchangeable, so, again, don't fret over it. If you need to swap it out, the old one will go right on the newer motor. You can tell by numbers stamped into the bottom of the pan. The later pan will in all likelihood not fit the 63 Valiant, as they take a specific pan. Since you already have it, just swap it on the newer engine. Take note of the oil pickup as it may be different and match the early pan, you may need to swap it, too. Never fear, it simply unscrews out of the block. You'll also want to make sure you clean the pan out good and the pickup too as they may have sludge buildup. That's about all I can think of right this minute. I'm not having a good health day today so forgive me if I left anything out. We have some good guys on here and they'll chime in where I left off if I did leave anything out. Good luck and if you run into a snag, just holler.
