Sorry but that sounds bad. Have you checked the fluid level and condition. Just from what you said I would say it's shot.

 

lentechautomatics.com

bring your wallet, but they are the best for AODs in the world. Been written up in several magazines in the last year.

Sixlitre

p.s./
not to add salt to the wound, but I'm just about top add a remote tranny oil filter to stave off exactly the same problem in my 86 OAD before it happens.

 

you say: *wont work when warm, feels like driveshaft fell off* and then: *no 4wd when warm*

, do you have NO drive when warm both rear and front driveshafts , or just to the front?
If thats the case, sounds more like youre transfercase and as far as rolling away in park, could be somethings wrong with the parking pawl in the trans.

 

after the tranny is worm and your driving down the hyway it seems like someone reached over and put it in N becuse it just wont go . stop and try to put in park it just grindes like there is no drive shaft hooked up. so you let it sit for half hour or so then it's just fine for about 10 minutes then the same thing happens

 

Um...... sorry, as boulder said....sounds bad!

 

i'm going to suggest that this is a transfer case problem, not a tranny issue. my friend's 81 did something similar to what you describe and it turned out his tcase lost its fluid and destroyed itself. also, here's something else to think about. the Park pawl is a mechanical device that's not linked to the hydraulics of the tranny. Unless you snapped the output shaft going to the t-case, that is the only way your park would not hold the truck. This would not explain the lack of "go" on the highway, so I dont think that's it. It's gotta be the output shaft or the t-case, not a hydraulic problem inside the tranny. For the helluvit, drop her into 4x4 and 4lo and see if she goes, that might cause a change. This would be a much cheaper problem than a busted tranny

 

i have to agree with Muddy, ive already fixed a park pawl (in my g/f'struck) and those are not the symptoms that occured when it snapped. If it broke youd know it, cause the tranny shifter would totally jam up, and leave you totally stuck in neutral, regardless of what the shifter said. Im gonna have to throw a vote for t/c problems