Mostly agree, but I think it would be significantly cheaper to shorten and balance the old shaft than to have a new one made up. At least, that was the case when I first put an 8 3/4 in my 65 Barracuda back in the seventies. Only reason I ever replaced that shaft was I switched to a later trans, then found out a Duster 340 manual trans drive shaft bolted right in despite the wheelbase difference between the Duster and my Barracuda. That's also when I found out about the difference in low gear ratios. Was an unhappy camper for a couple of years until I found out my original gearset with 3.09 low gear fit inside my newer trans.
