So my tranny's pretty old, and sometimes when I put the auto shifter into "D", the transmission won't engage.

Anyone got any tricks to make it happen?

The first time it happened, I gave it more gas, and it eventually went *CLUNK* into gear w' the rpm's ~3,000. It felt like a neutral drop.

So recently I've tried putting it back into park, rocking the truck back and forth, then trying again.

Any ideas (besides buying a newer truck)?

 

put it into OD when you are driving it
flush the tranny

 

Fluid full?, Change fluid and filter.

 

Sounds like your servos may be leaking or bad, and/or your line pressure is bad. Get it checked out as low line pressure and crappy servos and solenoids can cause wear and even outright breakage.

 

Uhhh check the transmission fluid level first. If that checks out ok take it to a shop and have it diagnosed, because it wont last much longer like that.