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The Aisin AS68RC is the six-speed automatic Ram bolted behind the 6.7 Cummins in the 3500 cab-and-chassis and the 4500/5500 medium-duty trucks from 2007.5 up through 2018 (the 3500 pickup got either this box or the 68RFE depending on year and configuration). It is a Toyota-designed, commercial-grade unit built to move real payload, and when it is healthy it is one of the more durable diesel automatics on the road. When it is not healthy, it is expensive, because parts are Aisin-specific and there is no cheap junkyard shortcut.
This page walks through what fails on these transmissions, exactly what a master rebuild kit should contain, where OEM matters and where a good aftermarket part is fine, the torque converter question, and what the whole job actually costs in 2026 whether you turn the wrenches yourself or hand it to a shop.
Common AS68RC Failure Points
The AS68RC does not fail randomly. It fails in a handful of predictable ways, and most of them trace back to heat, fluid neglect, or a truck that tows heavier than the original owner admitted.
- C1/C2/C3 clutch pack wear. The apply clutches cook first on hard-worked trucks. You feel it as a slip or flare on the 2-3 and 3-4 upshifts, or a delayed engagement into drive after a cold start.
- Overheating from a plugged cooler or a marginal factory setup. The AS68RC runs hot when loaded. Sustained high pan temps glaze the frictions and harden the seals long before the clutches are actually worn out.
- Solenoid body and valve body wear. Debris from a slipping clutch circulates and scores the bores. Harsh or erratic shifts and stored pressure-control codes often point here rather than at the clutches themselves.
- Torque converter lockup clutch failure. The converter clutch shudders or the lining sheds material into the fluid, which then contaminates everything downstream. This is why a converter replacement is rarely optional during a rebuild.
- Case-connector and internal wiring faults. The pass-through connector and the internal harness can chafe or corrode, throwing solenoid codes that mimic a mechanical failure.
If your truck is throwing limp-mode events or specific fault codes rather than a clean mechanical slip, read our AS68RC limp-mode fix walkthrough before you assume the transmission needs to come out. Plenty of these get condemned when the real problem was a connector or a single solenoid.
What's In an AS68RC Master Rebuild Kit
A proper master overhaul kit for the AS68RC is more than a gasket set. When you have the unit apart, you replace everything that wears as a system, because the labor to go back in for one cheap part later is the whole cost of the job. A complete master kit should include:
- Friction clutch plates for every pack (C1, C2, C3, B1, B2 and brake elements). These are the primary wear items and the reason you are in there.
- Steel plates / reaction plates to pair with the new frictions. Reuse of blued or heat-spotted steels is false economy.
- Complete seal and O-ring set including the piston lip seals, which are what actually hold apply pressure.
- Full gasket set plus the pan gasket and case sealing surfaces.
- Sealing rings (Teflon and metal-clad) for the pump, drums, and shafts.
- Bushings for the pump, shafts, and stator support. Worn bushings let shafts walk and kill line pressure.
- Filter (internal spin-clean / pickup filter). Always new, never cleaned and reused.
- Thrust washers / bearings where included in the tier of kit you buy.
Kits come in tiers. A "banner" or basic kit is frictions, steels, seals and gaskets. A "master" kit adds bushings, filter, and sealing rings. A "super master" or overhaul kit adds bearings, thrust washers, and sometimes a bushing kit. For a truck that earns its keep, buy at least the master tier.
Browse AS68RC master rebuild kits
Friction and Steel Kits Sold Separately
If your seals are still supple and you are chasing a specific slipping clutch, you can buy a friction module and matching steels on their own. On a high-mile truck it is usually shortsighted, but it is a real option for a targeted repair.
Check AS68RC friction and steel kits →
OEM vs Aftermarket — Where It Matters
The AS68RC is one of those units where the OEM-vs-aftermarket answer is not the same for every part.
| Part | Recommendation | Why |
|---|---|---|
| Frictions | Quality aftermarket (Raybestos, Alto, BorgWarner) is fine | These vendors supply OE-grade friction material; premium/high-energy frictions can even outlast stock behind a tow rig. |
| Steels | Aftermarket fine | Flat, hardened steel is a commodity. Just buy new, not reused. |
| Solenoid body / solenoids | OEM or Aisin-supplied | The pressure-control solenoids are calibrated tightly. Cheap copies cause shift-quality complaints and codes. |
| Torque converter | OEM reman or reputable HD builder | Lockup-clutch quality is everything on a diesel converter. See below. |
| Filter, seals, bushings | Aftermarket fine | These come in any reputable master kit and meet spec. |
The short version: aftermarket for the hard parts that are just steel and friction material, OEM-grade for anything with a calibrated hydraulic or electronic function.
The Torque Converter Question
Do not reuse the original converter on a rebuild. The converter is a sealed unit that traps worn-clutch debris and old fluid no cooler flush fully clears, and its lockup clutch is often already shot by the time the transmission slips. Reinstalling it drops that contamination straight into your fresh clutches.
For a stock or lightly loaded truck, an OEM reman converter is the safe default. For a truck that tows near GVWR or has any tuning, step up to a heavy-duty or billet-cover converter with an upgraded lockup clutch, which resists the ballooning and shudder that kills stock units under sustained load. We cover the failure symptoms and pricing in detail on the AS68RC torque converter replacement cost page.
Compare AS68RC torque converters
Rough Cost Ranges (2026)
These are realistic U.S. figures for 2026. Your numbers swing with region, converter choice, and whether the valve/solenoid body needs replacement.
| Item | Typical 2026 Cost |
|---|---|
| Master rebuild kit (frictions, steels, seals, filter, bushings) | $350 - $650 |
| OEM reman torque converter | $500 - $900 |
| HD / billet converter (towing) | $900 - $1,500 |
| Solenoid / valve body (if needed) | $600 - $1,400 |
| Fluid (ATF+4, ~18-19 qt with converter) | $120 - $200 |
| DIY parts total (typical) | $1,100 - $2,200 |
| Shop rebuild, out the door | $4,500 - $7,500 |
| Reman replacement unit, installed | $6,000 - $9,000+ |
The gap between the DIY parts bill and the installed-shop number is almost all labor and converter tier. The AS68RC is a heavy unit and a paid rebuild runs high because it is a commercial-truck transmission with commercial-truck parts prices.
DIY vs Shop
Rebuilding an AS68RC at home is doable for an experienced builder, but it is not a good first automatic. The clutch clearances are spec-critical, the solenoid body wants careful handling, and you need a press, the right bushing drivers, and a way to set converter endplay. If you are missing those, the tooling investment eats the savings.
Do it yourself if: you have rebuilt automatics before, you have a press and a clean bench, and you can source a properly reman converter. Your out-of-pocket lands around $1,100-$2,200 in parts and fluid.
Pay a shop if: this is your daily work truck, you cannot afford a redo, or you do not have the tooling. Insist on a new converter and ask whether the solenoid/valve body is being replaced or reused. That single line item is the difference between a rebuild that lasts and a comeback.
Either way, fix the cooling. Add or verify an adequate transmission cooler before you put the truck back to work, or you will be doing this again. See our cooler picks for the 4500/5500 Aisin trucks.
Rebuild Parts, Ships Same-Day
Master kits, frictions, solenoids, converters, and ATF+4 for the AS68RC and the rest of the Ram Cummins lineup. Same-day ship before 2pm Eastern.
Shop Gearbox Insider →FAQ
What fluid does the AS68RC take, and how much?
Mopar ATF+4. A full rebuild with a dry converter takes roughly 18-19 quarts to fill and set level; a pan-only service is far less. Only use ATF+4 — a non-spec fluid will cause shudder and shift complaints.
Is the AS68RC the same as the AS69RC?
No. The AS69RC is the newer, stronger six-speed that replaced it starting in the 2019 Ram HD. They share design DNA but parts are not interchangeable. If you have a 2019-or-newer truck, you want AS69RC parts, not these.
Can I just replace the clutches and skip the converter?
You can, but you are gambling. The old converter carries debris and a possibly worn lockup clutch that will contaminate your new frictions. On a full teardown, budget for the converter.
How long does an AS68RC rebuild last?
A properly rebuilt unit with a new converter, upgraded cooling, and disciplined fluid changes should give well over 150,000 miles even on a working truck. The ones that fail early almost always ran hot or ran the wrong fluid.