i just bought a 91 explorer 4.0, a4ld..with it on jackstands it is locked in forward..no matter which gear selected it goes forward with no upshifts, even in neutral and reverse and feels like in park also...i have worked on alot of older transmissions and figure the forward clutch (if it has one) is locked-up...having never worked on a a4ld before i was wondering if this is common, or if there could be another reason for this with a repair not involving trans removal...i already dropped the pan, no more than normal contamination in the pan, also checked the manual valve and it is free and the detent spring holds and looks good...i think i already know the answer but just thought i would check with some a4ld experts who may of had a similar problem with one... thanks..R.C.
i have glanced thru some older threads and didnt see this problem listed

 

You ought to post down the page a bit in the transmission sub-forum...

The A4LD has a drum and sun gear as the first input. The drum, when stopped by the band, will put it in overdrive. It is possible the sun and planetaries have crunched and locked up, which would ... make it not work. Not gonna try to figure out what you'd have then, but it wouldn't be right, and could possibly lock up the transmission as the other stuff[tech term] wouldn't be set right.
If you don't have reverse at all, I don't think you would have any forward gears at all,as the rest of the gears have lower apply pressure than reverse.. Unless the rearmost band has broken, the strut fallen out of place, or the servo broken or really leaky.
The A4LD is noted for the center support seals wearing a groove in the support or leaking. They then lose pressure and the clutches/steels fry.

If you have forward apply in all gear settings, either pressure is applying from the get go, or something is locked. To find out, bypass the neutral safety, taking all precautions to avoid running into anything, and see if it starts to move instantaneously, rather than waiting for pressure in the system to build up and apply a band, servo or clutch pack. If it moves right now, I'd expect something locked. The 'right now' is different from the few seconds it takes to engage D or R when you move the control.
But the one I worked on had burnt clutches due to the seals hardening and losing pressure.
tom