First what is it ? or am i actually gonna haveto craawl under there and measure? 350 chev sb th400 whats the driveshaft lengh thanks!.

 

It's going to depend on what tranny yoke you use. I have 2 different yokes that will give me 2 different driveshaft lengths.

You need to slide the yoke into the tranny all the way and pull it out 1". Measure the length between the u-joints center to center. That's the total length. Don't guess.