I bought a 1986 dodge d150 it has 000.296 miles on it I found it in a barn brought it home and started messing with it got it to run with a little love and a whole lot of cussing im a ford guy so im used to turning wrenches but for the life of me I can not figure out why it shifts so hard that It will kill the engine when I shift it into first or reveres any hints to fixing this would really help

 

Sounds to me like a Valve Body issue at this point.....

 

How does the engine run in Park or Neutral? Does it rev OK or does it stumble. It seems to me that the tranny is pulling the engine down when you shift gears and if the timing is correct on the engine and it runs fine, Bob's right in thinking that the tranny is the issue. Could be the torque converter went south, the valve body is stuck causing dual band engagement or parking pawl is always engaged. Drop the pan and check it out. Filter clogged? Shift rooster moving to the right detents? Pan full of metal,gunk, or tranny parts? Servo let go or stuck? You don't have to remove the tranny to check these thing out but while you're in there remove the valve body and clean it inside and out. Make sure not to lose or misplace the check ***** on reassembly. You can download diagrams and instructions on line.