Good morning all! I have a '97 Ext cab 4.6............... Because no good deed goes unpunished, I lent a buddy of mine my truck, and the rear end went out on him. Any suggestions on what I should look for on the used market? I searched the forum and I have to admit the gear ratio talk is mostly over my head. I know from factory it came with the 8.8, but if I'm going to replace it, I want it to be with something robust, as I only want to do this once. I do very little offroading, tow light items on occasion, and primarily use this as an extra vehicle/work truck. Thanks in advance!

 

Look at the axle code on the driver's door jam and that will tell you what ratio and size it has. there should be tags on the rear diff cover that will tell you the size and ratio. If the OE rear lasted 20 years, there is no reason to upgrade is there? But, these trucks with the 5.4 engine came with a 9.75" rear and that should be an easy upgrade. I'm not sure exactly what needs to be changed to make it fit but should be minimal I think. I'm sure someone who does know the differences in installation will chime in soon.

 

Awesome, great info, thanks!

 

It's a 8.8, and no need to upgrade to a 9.75. Best to replace it with something identical. A complete rear out of a 97+ truck with drum brakes and a 4.2 or 4.6 should bolt right in. You just should make sure it's the same ratio.

 

It doesn't need to be the same ratio. The speedometer will read the same as long as the tire height is not changed. So you could bolt in an upgrade to rear disks and 3.73 LS if you want.

 

Yes, it does need to be the same ratio unless you change the VSS drive gear.

 

Is this 2 wheel drive or 4 wheel drive?