When going to a V8, there will be more stress on the driveshaft. If youplan to really launch your car hard, especially with a four-speed, westrongly recommend getting the sturdier V8 driveshaft; you can eitherhave one made or locate one from a V8 car. Under normaltransportation-only type driving, the smaller one would probably workfine, but who of us does that? Also keep in mind that Mopar offered twodifferent size universal joints: the 7260 is the smaller unit, while the7290 is larger and more durable; these need to be strong. Finally, ifyou are using an automatic with a fairly stock converter; this will be alittle more forgiving since it's a "fluid coupling system" instead of adirect gear. The verdict: Better safe then sorry; upgrade to thestronger styles as soon as you can.