axle splines??
 

I've recently acquired a 1989 Dodge D350 Cummins diesel 2wd with a nice dump body. Unfortunately, it has lousy tires (easily remedied) but I’m thinking I need a locker for use on the farm, since it now gets stuck at the drop of a hat (and we have serious mud issues). I was looking at Powertrax lockers since I really don’t want to re-set up the axle, but I’m not sure if I need a 35 or 37 spline. It is a Dana 80 dually 12x3. Can anybody tell me more info without having to pull an axle and count? Much thanks in advance!
-jon

35