Weird transmission problem: no D, some R, L is going backward?????

I am going with the splines stripped out on the reaction carrier . Common on vehicles that are subjected to not coming to a complete stop before changing directions . Not saying this is the fault of the op but would explain the symptoms .
Considering the loss of forward ranges and the transmission trying to reverse in low gear , you can bet that the planetary is missing its control brake for drive range . Internal mechanical problem .
These transmissions are a dime a dozen on craigslist . The Aisn Seiki A750E series are an extremely tough and well built slush box and is why the market is flooded with them . If you keep them clean and I mean very clean , you shouldnt have problems . Full transmission service every 25,000 miles minimum and a good size aftermarket transmission cooler .

Got some info here that may help
https://www.tacomaworld.com/threads...th-pics-for-second-gen-4-liter-trucks.289913/

 

My transmission went out at 150k, I had it replaced with a remanufactured unit and Valvoline MaxLife ATF was used, I've put almost 30k on it with no issues. I put well over 120 miles per day on my truck as well.

 

This...

 

Forward clutch pack, reverse does not engage the forward pack for obvious reasons some thing mechanical broke I don't believe it is pump or clutch issue. High clutch and reverse clutch makes it go backwards. Fluid did not cause it. I'm not that up on the 5 spd but it's likely the sprage blow up and that is why it tries to move in L

 

Hmmm thanks for the info guys. I do come to a complete stop changing gears, but it is lifted a good bit and regeared diffs so there's definitely more of a strain on it than normal. I did also notice that it hesitated to upshift from 4th to 5th (would take a full 10 seconds to shift up sometimes while over the standard RPM range) but didnt really seem to be a problem, more of a nuisance...

Got a replacement 2015 4.0 4wd trans with 5k miles to replace it.... Greedy bastards stripped the transfer case off of it though so hopefully its not the transfer case.

Side note; does anyone know of a good way I can fully fill the transmission COMPLETELY (so that there are no bubbles in the line) aka purge the system so that it doesnt burn or break anything on initial startup?

 

You cant fully fill the transmission before start up because the transmission pump needs to be turning to charge the torque converter and valve body . put 5 or 6 liters in the pan before start up . You could remove the torque converter and add some fluid into the converter but it will almost guaranteed leek all over the floor from the cooling lines during installation .

 

will it damage it if I fill it and start it? .... basically whats the best way of filling it back up?

 

Its *definitely NOT* the transfer case. Nothing in the transfer case can make it go backwards when you have it in forwards.