Blew my transmission in my 98 4x4 4.6 awhile back and just changed it with a used one.
Filled it with fluid took it for a test drive I noticed it wasnt shifting passed second it would just slip into neutral.
noticed I put too my into it so I drained some out. I noticed the colour of fluid was kind of milky so I ended up taking 5 L out by disconnected the top line from the rad and running a hose to a jug and running motor till it stopped coming out.
I filled to the proper spot with fresh fluid.
I reset the codes by disconnectin my negative terminal for 15 min.
fire it back up and soon as I start moving moving light starts blinking again. So I parked it and I assume its gonna have the same issue.
I'm not really sure where to go from here I cant take it into a shop since i live in the boonies.
any advice would be helpfull

 

Why? It’d be really helpful to have those to help you out with.

We can’t even assume you put in a compatible (electronically) transmission in the first place.

 

Always find out what the codes are, that's the only starting point you have.

 

I pulled out a 4r70w and put a different one back in... I'm assuming the exact same transmission would be compatible.

And the reason I reset the codes is because I blew the old transmission because of a hole in the rad and it overheated and i lost forwards gears. So I reset the codes thinking it was still in limp mode

 

What year was the transmission you put in it? You've assumed wrong. There are differences.

 

My truck is a 98 4x4 4.6. 4r70w trans
the truck the other trans is from is 99 4x4 4.6. 4r70w trans.
there shouldnt be an issue with the electrical being different.

 

Wiring is the same, or 98 and up, but the transmissions are not. There are differences for 97 is by itself. So is the 98. 99-03 will usually swap without problems The 97 and 98 are analog reading for the speedometer. The 99 and up is read digitally to the speedometer.

 

Yep!

 

Odd maybe but I bring this up only because the OP doesn't identify where he's from. Wasn't there something about the 4R70W that wasn't emissions compliant for California and some other states? IIRC in those few states it had to do with emissions mapping effecting gear shifting and how the TC locked up in OD and how it would unlock for additional torque. Anyway, there was something about the PCM electronics requiring specific transmissions built for the state emission standards for the electronics and transmissions to work together. This isn't something I had to deal with and I admit I may have this wrong but I think it's why in CA and some other states vehicles predominantly came with AODE or 4R100 transmissions.

 

/AOD/AODE became the 4R70W, which became the 4R75. The C6 developed into the E40D and then became the 4R100.