I recently drove a new to me 1992 F250 back home.
7.3idi w/hypermax turbo and e4od
First issue of the trip, the volt meter read on the low end and the dummy light came on. Made it to hotel, and next morning wanted to swap alt with none around. Put new Batterys in with the thought of making it somewhere to get an alternator, started truck, warmed up 5-10 minutes. Backed out of spot and truck fell out of gear. Could move shifter wouldn't go in gear. Dipstick showed it was overfull. Waited a while longer in the middle of the lot and it decided to shift after warming up for a long time. Drove the rest of the way and it would always go in gear afterwords.

While driving truck it would run 2300 ish rpm at 65-70. Generally has a real loose feeling. Shifting seems odd, it constantly shifts up and down up hill. (Feels like a shift) When going uphill it would shift up for a bit and run 65 at only 2000. Wouldn't shift down unless i backed off pedal slightly. Coming down a mountain, it starts charging and has since. Truck now seems to shift a little better but still seems sorta loose and shifts funny uphill. Speedometer will occasionally bounce/flicker. Rear abs light is on. When letting of throttle, tach will fall to 400-500 sometimes or read nothing at all. Previous owner had new transmission installed with only a couple hundred miles on it. Any ideas apprieciated. Records in the truck show the alternator and regulator where replaced as well.

 

Could be a bad sensor in the rear end since your speedo is affected.

 

Sounds like you have a few problems and a wiring issue for sure
I'd plug a NGS into it and check the codes in the powertrain and see what the NGS says about the E4OD
That would be what the Ford dealer would have done back in 1992
\Now the dealer would use their updated laptops
Either way, you'll have trouble trying to do any testing on that 1992 IDI without some special tools (Rotunda magnehelic gauge)
A paperclip may pull a few codes for you
Ford diesels do not run a EEC 4 processor but they have a self test connector for the E4OD
Here's mine

 

It is an EEC-IV and is called a Transmission Control Module(TCM).

 

Thanks guys, im going to look at the speedo sensor and possibly get a ngs tester. Is there anything specific Ill need if I get one?

 

Paper clip, a lot cheaper. NGS is old, outdated, and any thing used, is being sold because they do not work any longer.

@manicmechanic007 is literally married to theirs' and doesn't know any different and is all they recommend.

 

New Rear wheel abs sensor fixed the speedo problem

Not that it helps anyone, but everything was wrong with the transmission. I finally broke down and took it to a trusted local shop. Broken snap rings, chewed up pump, clutch pack assembled all wrong and some bad electrical connectors. I'm way further into this truck than I intended, but it goes into gear and shifts much better now.

However the cruise control still pulses quite badly, is there any common causes to this?

 

The speed sensor
The VSS in the rear end is also the cause of any fluctuating speed with your speed control
* You monitor the VSS voltage at 60mph and see if it holds steady voltage (monitor A/C millivolts)
Any fluctuation in voltage will result in the speed control fluctuating, and not holding a steady speed
One more reason the NGS is so handy
Without one
You will be running jumper wires to a DVOM in the cab from your speed sensor to test the voltage
Then you get to test that voltage in 3 spots