If you get a rebuilt converter, it will have the new sprag in it - and you can test it's effect if you happen to have a spare input shaft available to you. Just insert it into the converter and even though you cannot activate the clutch, you'll fel the drag of the new sprag in one but not the other direction.
In any situation, I'd prefer to NOT get the newest bad idea of having a Kevlar friction material clutch in it - it requires too much fluid pressure to hook up and the front pump is max'd out just making the trans work in the first place. Any more taxing of that incredibly weak and poorly designed pump will shorten it's life a lot.
'Shift Kit' is a registered trademark/name by Gil Younger, whom I have had the extreme privilege of meeting in his (and my) early days of building transmissions.He had a project going on called: "Operation Bootstrap" concerning the THM 700R4 units that were not living very long after the warranty from GM expired and he worked on it until he got it right.
I still have some of the very yellow and grease stained hand-written notes he and I sent back and forth to each other in @ 1969 or so.
He made - don't know if currently so - a pretty good shift improvement kit for the 4L and 3L versions of that transmission, and they weren't just an improvement, they also created a lot of reliability too.
A legal Trans-Go 'Shift Kit' will be green and white with Gil's smiling face on the box exterior. Accept no substitutes.
You won't ever get a crisp shift from this unit --- as there's too much monkey motion in it and it should be congratulated for just finding the next gear, not chirping the tires.
Your 4L unit is a sore spot to a lot of shops for several reasons: (but don't despair, it can work for many years and miles)
New parts are as rare as a whore in church
Used parts are worn out in non-obvious places that really count, and although there are repairs for them available, they are very expensive.
There are a lot of vague ideas about what these units can do, but the weakest link is that rotten OD unit in front of the rest of the unit. Bad place to put it is an understatement.
GM really screwed this unit by prostituting their designs and working with OPEL/NSU/BMW engineers on it too. This unit was on multiple shelves for many years, just gathering dust and taking up space when some idiot with a slide rule talked the bean counters into putting it into Isuzus and a few other LIGHT WEIGHT vehicles.
The co-mingling of ideas and the whipping by the accountants produced a real illegitimate child, fathered by two sets of ideas mitigated by expenses and cost over-runs.
EVERY one of these units has a built-in demon who will break it, keep it from driving out of the shop and/or screw up shift patterns and reliability many times over. It may not work well after the (first) (second) (third) rebuild if the bench guy doesn't look carefully at all the ring and shaft stators and hubs that need perfect seals to keep the fluid leaks to a minimum. Remember that this front pump is at it's peak capacity already, and if there's the tiniest leak, something won't get enough pressure or flow - and die.
I personally would NEVER put scarf-cut Teflon rings in this unit at all. I would only install cast iron, locking Vandyke style rings in it.
I would never put an un-inspected shaft in this unit until I ran my bore-o-scope through it and measured the shaft/hub for previous ring groove wear. ANY wear trashes the shaft as far as I am concerned unless I could get it metal sprayed and re-machined back to OE specs.
Shaft leaks and stators that need new metal are the biggest failure point for any transmission - well maybe not an Allison 'cause they run on designed-in internal leakage - but your unit is hurting for fluid with that weak pump in the first place --- so ---------
One might be of the impression that I dislike the 3L and 4L series - I do not.
I only dislike everything built by Chrysler.
