I'm having a little trouble with the tranny in my '92 CTD. It's not clear if the tranny or the converter is the culprit.
When cruising in OD I can feel the RPM is a little high and it's reflected as slightly higher readings on the boost gauge. Sometimes I can accelerate a wee bit then back off. When I resume speed, the rpm and boost is where it should be. I can't feel the transmission slipping or catching.

The truck isn't equipped with a tach so an exact rpm figure is out. When the RPM is running too high there is a distinct lack of power. I really have to push it to go from 60 to 75 mph.
When hauling about 2000 lbs in the bed I had to floor it to get from 70 to 75 mph on a slight incline. Other times in that trip it was fine and acted normal.

I don't know if the converter is slipping or if the OD is used up. The fluid is topped off and does not smell burned.
I've had a 727 die on me in my old car but this one does not "catch" like the slipping 727 did. All non-OD gears are fine.

I know the gassers have problems with the converter clutch failing and having the debris take out the OD.
This transmission does not have the third wire for the converter clutch.

 

Our 518's aren't called 'Slush-o-matics' for nothing. They are notorious for having poor efficiency; 70%? (don't quote me). Add a high OD gear and the problem worsens.

 

These slush-o-matics are built off the 727, one of has been backing my twin turbo 440 cranking out 647 hp and 742 ft/lbs at the wheels for several years. It's got nothing more than standard rebuild parts in it.

I simply need to know if the truck's tranny is spent or if I'm looking at a converter issue.
I didn't find any debris in the pan.

 

Its not a "converter issue" , its a sucky factory converter.

Dodge put a slippy converter that stalls too high behind a DIESEL engine, The converter comes in about midway in the TQ range from what me and my dad have noticed.

Doesn't really anything to do with the tranny. The torque converter is simply too unefficient.

An aftermarket converter would cure your problems and make it feel like a different truck with a load behind it. That and a 3200 rpm gov. spring and you'll be pullin hills at 90mph

I recommend Dave Goerend Torque converters, He specializes in Dodge trans/converters and actually knows 1st gens pretty well. Keep in mind we're talking non lockup here and that sets alot of trans companies apart, knowing what YOU have. he doesn't list the 89-93 converters on his site but you gotta talk to him on the phone. He makes an 89% converter that is $550 and $650 with a lifetime warranty.

Slush-o-matic meaning the converter feels like its full of slush

 

The truck just started doing this. I've had it in 37 states and run it over 269,000 miles. You can't tell me it's "an auto trans thing" and that they all do it. This is a new condition. Either OD or the converter is dying.

This happens when driving empty. It's also happened when driving with a yard of rock in the bed. It's intermittent and can slip or hook at any given time in OD.

I'm trying to figure out what's failing. There's no point in dropping in a converter I can't afford if the transmission fails and fills it with trash. At the same time, I can't afford to build the tranny if it's a converter issue.

I was hoping to get a better idea without having to tear down the transmission.

I've been through the old 727s before but that was many years ago. I can probably rebuild this one too but it may take more than a weekend. Unfortunately, I can't afford a tranny and converter right now. I've got to do my best to make it work.

 

There is no clutch in the convertor to fail these are non lockup units.