• If the shifter has a P-R-N-OD-D-1 pattern, the transmission must be an AOD (applicable to 1980-1993 vehicles).
• If a 1989-1993 truck has an Overdrive Cancel Switch and a P-R-N-OD-2-1 shifter pattern, then it is equipped with an E4OD transmission. With the possible exception of some 4R70W equipped 1993 E-150 vans with 5.0L SFI engines (The existence of a 1993 4R70W van is unsubstantiated).
• 1994 and later vehicles with four speed automatic transmissions will all have an Overdrive Cancel Switch and a P-R-N-OD-2-1 shifter pattern, but may have either an E4OD or a 4R70W transmission. All 4.2L, 4.6L and some 5.0L engines use the 4R70W transmission, while diesel, 4.9L, 5.4L, 5.8L, 6.8L and 7.5L vehicles always use E4OD’s. You can measure the transmission fluid pan to determine which transmission you have if identification information is not available. A 4R70W transmission pan has an overall length of just under 15 inches, while an E4OD pan is much larger, measuring about 20 inches in overall length.

The E4OD has seen many changes and updates since its introduction in 1989, but most later transmissions will prove reliable with nothing more than our ReCal-Pro™ E4OD valve body recalibration kit and a "low pressure drop" auxiliary oil cooler (an OEM auxiliary cooler, if installed, is usually adequate). Baumann Engineering supports the E4OD with the Baumannator TCS™ electronic transmission control system (which provides complete control of all transmission shift points, as well as torque converter clutch operation and part-throttle shift firmness). Baumann Engineering can also provide custom-built torque converters for the E4OD transmission as mentioned in the "Torque Converter Upgrades" section of this guide.

If it becomes necessary to overhaul your E4OD transmission, you should perform as many updates as possible if it is a pre-1995 unit. E4OD component updates include, as an example, the following items:

• Improved (thicker) converter clutch piston (circa 1994), prevents the formation of cracks which relieve fluid pressure from the apply side of the clutch, causing it to slip and even bluing the outside surface of the torque converter in extreme cases. Ensure that your new converter contains an updated OEM or "LuK" brand heavy-duty clutch. This can be difficult, as many torque converter suppliers and remanufacturers may not use this new style of clutch.
• Higher displacement front pump (for 1995) provides more fluid capacity for faster engagement of reverse and greater lube flow.
• New (for 1994) 4-pinion overdrive planet and input shaft assemblies replace older 3 and 4 pinion units which tend to develop cracks in the carrier under heavy loads.
• Center support update kit (for units built from 1989 through part of 1994) replaces wear-prone bushing with a ball bearing and contains a new overdrive stub shaft.
• Stronger overdrive clutch cylinder snap ring which will not dislodge.
• Revised sun gear and rear case bushings (circa 1992 model year) provide longer wear life and better lubrication.
• Four pinion planet carriers (first used in 1992 model year)
• New forward clutch friction plates with hardened internal splines cure "chatter" and "no-drive" conditions in E4OD and some later C-6 transmissions.