The rebuild manual for a GM TH350, TH400, 700R4 or early 4L60E tells you to pull the pump with J-24773-A and check end play before teardown and again at assembly. This is that tool. Also called SST-1055 or T-1055, it threads into the pump and draws the pump support assembly straight out of the case, then does double duty as the end play checker once the geartrain is back together. If you are working on a Silverado, Sierra, Tahoe, Suburban, S10, Blazer or Camaro that is slipping, slow to engage or whining with engine speed, this is the tool that gets you inside without damaging the case.
What this tool does on a GM pump
On these GM units the front pump body and its stator support are bolted together and pressed into a close-fit bore at the front of the case, with an outer O-ring sealing the gap. The SST-1055 threads into the pump so you can lift the whole assembly out level, so the bushings and stator splines are not scraped and the case bore is not chewed up by screwdrivers. On the 4L60E that pump is a 13-vane, variable-displacement design, and it supplies all of the pressure the clutches and band need, so a scored bore or cracked body is not something you want to discover after assembly.
Why the end play check matters
End play is how far the input and geartrain can move fore and aft between the pump and the case. Too little and thrust washers and bearings run hot; too much and the drums can walk, wear bushings and load parts like the reaction sun shell, a known 4L60E weak spot. Checking it before teardown tells you whether something inside is already worn, and checking it at assembly confirms your selective washer landed in spec before the pan goes on. To use this tool for end play you need the J-25022 or T-1068 adapter to attach to the output shaft; it is not included.
Symptoms that bring these units apart
- Slipping in all gears and delayed engagement into Drive or Reverse
- Whine that follows engine RPM and low line pressure on a gauge
- No 3rd or 4th gear from stripped sun shell splines on a 4L60E
- Burnt 3-4 clutches, especially behind a modified engine
- Clunks or a drum walking forward from excessive end play
How to confirm before you tear it down
Run a line pressure test and road test the shift pattern first. Low pressure in every range suggests a pump or regulator fault; a missing 3rd and 4th with a working 1st and 2nd points at the sun shell. With the pan off, measure end play before you pull the pump so you know what you started with. Our 4L60E common problems guide covers the sun shell and 3-4 clutch failures, and the pump rotor and bushing wear guide covers what to inspect once the pump is out.
Fitment
The tool is listed for GM 200, 200C, 200-R4, 250, 250C, 350, 350C, 375, 400, 3L80, 425, 3L80-HD, 700-R4, 4L60 and 4L60-E. The important exception: it will not fit the late 4L60E pumps that use a smooth stator shaft. If you have a later unit, check your stator shaft before ordering, or use a clamp-jaw style puller instead. Vehicle coverage for the 4L60E is on our 4L60E parts page; if you are unsure which pump your unit has, send us the year and VIN.
Install notes and what to replace alongside
Before the pump goes back in, inspect the thrust bearings and washers between the pump and the input drum and replace anything pitted; the 4L60E thrust bearing kit covers the common ones. Worn pump or stator bushings can be swapped with a master bushing driver set. Align the pump halves with a band tool, fit a new outer O-ring, gasket and front seal, recheck end play with this tool, and prime the pump with Dexron VI before first start.
