It’s more than likely that you’ll need to have a new driveshaft made once your engine and transmission are in place. It’s important to ask for the yoke from the donor vehicles driveshaft. Find a reputable driveshaft shop in your area, and use their worksheet to measure for a new shaft. Take the yoke and the measurements to them and have a custom shaft made. Generally this costs about $200-300, but it’s well worth it to have a new, perfectly balanced driveshaft for your new drive train.