48RE Transmission 4WD Overdrive Extension Housing

A cracked tail end on a 48RE usually announces itself as a red puddle under the transfer case, a seal that will not stay dry no matter how many you install, or a transfer case that has started to shift on its mounting face. On 2003-2008 Dodge Ram 2500 and 3500 4x4 trucks with the NP271 or NP273 transfer case, the cure is a new rear housing, and that is what this is: the cast aluminum 4WD overdrive extension housing, supplied with the case gasket, the round transfer case gasket and the seal shown in the photos. Reference numbers on the listing are 509316AA, 05093166AA and D22770GAD.

What the overdrive extension housing does in a 48RE

The 48RE is built in two sections. The main case holds the three-speed geartrain from the old RE family, and a separate housing bolted to the back of it holds the overdrive section that gives the truck fourth gear. On a 4x4 truck that rear housing has a second job: its back face is where the transfer case bolts on, so it carries the full weight of the transfer case and every driveline shock that comes through it. The 48RE also runs higher line pressure than a 46RE or 47RE once overdrive or converter lockup applies, which Sonnax puts at roughly 22-28 psi of rise, so the housing has to stay true and sealed under more pressure and more torque than the lighter RE units ever saw.

Symptoms that point to the housing

• Fluid weeping from the joint between the transmission and transfer case, even after a new seal
• A visible crack in the casting, often near a mounting boss or bolt hole after a hard driveline hit
• Stripped or pulled threads where the transfer case studs or bolts go in
• Transfer case misalignment, vibration or a clunk on take-off that traces back to a loose or damaged mounting face
• Low fluid on the dipstick with no leak at the pan, cooler lines or front pump seal

How to confirm it is the housing and not just a seal

Clean the whole rear section with brake cleaner, drive until the fluid is hot, and look for where the wetness starts. A drip from the transfer case vent or its own seals is a transfer case problem, not this part. Check the housing face and bolt bosses with a light for hairline cracks, and try every fastener; a bolt that spins without tightening means damaged threads. If the leak is coming from the seal area, pull the seal and look at the bore: scoring, pitting or a bore that is out of round will eat a new seal quickly. Low fluid from any leak overheats this unit fast, so read our 48RE Cummins transmission problems guide and check the clutches if the truck was run low.

Fitment

This housing is listed for the 48RE in 2003-2008 Dodge Ram 2500 and 3500 four-wheel-drive trucks built with the NP271 manual-shift or NP273 electric-shift transfer case, behind the 5.9L and 6.7L Cummins and the 8.0L V10. It does not fit trucks with the NP241 transfer case, and it is not a two-wheel-drive tailhousing. Confirm your transmission is a 48RE and not a 68RFE, read the transfer case tag, and compare the part number cast or stamped on your old housing before you order. If you are unsure, send us the year and VIN and we will check it. Browse every part we carry for this unit on the 48RE parts page.

Install notes

• The transfer case and rear driveshaft have to come off first; support the transmission before you unbolt anything.
• Clean the main case mating face completely and use the new gaskets supplied; do not stack old gasket material.
• Install the new seal square in its bore with a proper driver, and lube the lip with ATF+4 before the shaft goes through.
• Torque fasteners evenly in a crossing pattern to the service manual value so the casting is not pulled out of flat.
• Refill with ATF+4 only and check the level hot, at about 180 F with the engine idling and the selector in Neutral, as Chrysler specifies for the RE family.

If the overdrive section is apart anyway, it is the right time to inspect the clutches and drums. A 48RE master rebuild kit for 2003-2007 covers the seals and frictions, and a 2003-2007 48RE input drum is worth having on hand if the old one shows heat checking. For shift complaints after the job, see 48RE Ram 2500 Cummins shift problems.

Will this housing fit my truck with an NP241 transfer case?

No. The listing is specific to the NP271 and NP273 transfer cases used on 2003-2008 Ram 2500 and 3500 4x4 trucks. NP241 applications use a different rear housing.

Is this for a 2WD truck?

No. This is the 4WD version with the transfer case mounting face. Two-wheel-drive 48RE trucks use a tailhousing with a driveshaft yoke seal instead.

What comes with it?

The housing comes with the gaskets and the seal shown in the product photos. Transfer case hardware and fluid are not included.

My seal keeps leaking. Do I need the whole housing?

Only if the seal bore is scored, pitted or out of round, or the casting is cracked. If the bore is clean and smooth, a new seal alone is the cheaper fix. Inspect the bore before you buy.

What fluid does it need after install?

ATF+4. Chrysler warns that a non-specified fluid can cause poor shift quality and shudder. Check the level hot with the engine idling in Neutral.

How do I make sure it matches my truck?

Confirm the transmission is a 48RE, read the transfer case ID tag, and compare the part number on your old housing to 509316AA, 05093166AA or D22770GAD. Send us your year and VIN if anything does not match.

• 48RE Cummins Transmission Problems: Failure Points, Upgrades, and What Actually Breaks
• 48RE Ram 2500 Cummins Shift Problems: Diagnosis and Fix
• 48RE Ram 3500 Cummins Common Problems and Fixes
• 48RE Speed Sensor Symptoms: Output Sensor Failure and P0720