Wait wait wait. This....
... is in all likelihood your problem. The light switch/connector should NOT go in either way; the connector face should be somewhat "D" shaped. I suppose it's possible to force it in in the wrong direction. That switch is, in effect, two switches. In 4HI, some part inside the t-case pushes the plunger halfway, which connects ONE of the terminals to the base of the switch, which grounds that circuit. That should turn the "4x4" light on (but NOT the "LOW RANGE" light). In 4LO, that plunger is pushed further, which grounds BOTH terminals, which turns BOTH lights on. The "LOW RANGE" light wire also goes to the TCM, which tells the tranny to shift at lower speeds.

So imagine if the connecter were plugged in backward. You shift to 4HI, the plunger goes in halfway, that terminal on the connector, which SHOULD be grounding the "4x4" light circuit, is instead grounding the "LOW RANGE" light circuit, and in turn, is falsely telling the TCM that you're in 4LO.

So before going into any surgery with the speedo cable, gear, sensor, etc., turn that connector around 180 degrees and see what happens.

 

He already did flip it around. I was hoping it was that simple too...

 

Eeek, misstd that!.....

 

Haha! Easy to do when the threads get lengthy. Yeah, got that sorted out. Almost done updating my charging system. Should be able to drive the beast tonight and see if the speedo gear fixes the issue

 

also, When I removed the ring gear from my new/used T case, It was the same yellow gear but its pretty worn down and almost flat in some. That explains my speedo needle jumping around, but could that also affect the shifting?

 

 

Well I'm going to assume that Ford color codes its gears just as GM does. If that's the case and they were both the same color then I would assume that it wouldn't make a difference.

Is that shift thing that the E4OD trucks have on the throttle properly adjusted? FIPL maybe? Don't remember, I have a 5spd so I haven't paid much attention to the auto specific stuff...

 

It all started after i replaced the T case so I just wanted to eliminate all possible T case related causes. If this aint the fix, then Its on to TPS/FIPL. last time I tested it, it was good. But, that don't mean it STILL is

 

Yeah I know but I'm kinda out of ideas...

 

No worries and thanks for the help!
IT'S FIXED!! It was the ring gear being worn. She shifts real nice once again!
Thanks everybody! Beers on me!

 

Awesome! So glad to hear that!

(So how far do I have to drive for my free beer he he he)

 

eastern washington. I'll keep it cold for ya