The 4L60-E derives its designation from its specifications: 4-speeds, Longitudinally positioned, 6000 lbs. GVW, Electronically controlled. These transmissions sees factory service in GM’s larger vehicles and trucks up to 8600 lbs.
The strength of the 4L60-E has turns out to be remarkable. Now a mainstay of the transmission building aftermarket, the 4L60-E is capable of transmitting impressive power from both truck and performance car applications.
The 4L65E transmission is almost identical to a 4L60E transmission. The main difference is the 5 pinion planetary gears in the low reverse planetary setup over the 4 pinion planetary gears in it’s predecessors. Mathematically speaking this an overall improvement of 20 percent over the 4 pinion planetary gears.
Realistically speaking it is not easy to tell the difference between the two units looking at the outside. Without knowing how to read the Identification numbers on the tag riveted to the outside of the case, ID is impossible. Relying on the dealership or a qualified transmission replacement company to make sure you get the correct unit. It is not unheard of to sell someone a 4l60e transmission in place of a 4l65e transmission.
Installing a 4l60e inplace of a 4l65e is actually downgrading your vehicle. In the case of a work truck or a family car, reliability is everything, including safety issues.
Speaking of reliability. I had a customers car towed into my transmission shop several years ago. At first I though it was towed to the wrong shop. It had been in a mild accident. Not very serious looking, but obvious. It turns out the problem was that the transmission was replaced by a shop about 600 miles away on a trip to see some family. The shop used a 4l60e in place of the 4l65e transmission, which came in their vehicle.
Six months later, which was the date the car was towed in, the mother of 2 small children
Chevy Transmissions
started to make a left hand turn on a major intersection. Half way through she saw she could not make the turn safely, so she put the vehicle in reverse to back up. Reverse broke instantly, causing no movement. She was hit very mildly by an oncoming driver who has slammed on the brakes, but ended tapping the right front fender.
No one hurt fortunately, all people involved were terrified.
It is easy to see why the correct transmission is just as much a safety issue as a performance and reliability issue. I do not know what turned out with the shop who put the wrong transmission in her vehicle or why. The end result was to buy on of our Chevy 4L65E transmissions, the correct model this time. The experts at GotTransmissions.com identified the correct transmission and sent us one ASAP. She elected to buy the nationwide parts and labor warranty. Call 866-320-1182 and speak to qualified expert.
