Auto trans shift linkage

[Cheyenne1010]

My name is Robert,I got a 1973 chevy cheyenne with 350 engine and 350 transmission.everything is stock on my truck.
   The problem I'm have is with the shift linkage.i have tried doing a adjustment on it but whenever I do the adjustment for p ark I'm unable to get L1 and if I do adjustment on neutral I'm able to get L1 but when I put it in park it's not fully engaged because when I'm in park with key removed and steering wheel lock,I'm able to pull shifter back and pull it down and it pops into reverse.its all original  parts for the linkage.any ideas guys will be appreciated,thank you guys for your time,

[MIKE S]

First thing I would do is identify if you have any worn parts in the linkage. With the column lever in neutral, does the lever seem to have a lot of movement going towards reverse and drive. Check to make sure the rubber grommet on the linkage under the hood were the rod hooks into the column is not worn. The lever that sticks out of the column that goes to the linkage could be worn were it is attached to the inner shift tube in the column. Wiggle it to determine if it has play. Check the cross linkage that goes from the frame to transmission. Is the plastic bushing and spring on the frame side intact or excessively worn? Is the U shaped bracket on the trans selector shaft tight on the shaft? Is the linkage that goes thru the U worn. Inside the trans there is also a nut that holds the rooster comb to the shaft on the linkage. That is known to come loose and cause play.

[Scott91370]

Finding a good diagram of the entire linkage so you can compare all the parts that Mike mentions would be your best bet.