I had the same problem with my build. I had to get a custom drive shaft made. I am running a sbc with a 700r4 transmission. I ended up with a driveshaft that was 39.25 inches long. The issue with ff sending you the driveshaft is you will not get the correct ends. I had 4 driveshafts sent to me and all of them were wrong. I think the shop charged me $150.