Hello everyone. I have a 99 Supercab with 4.6l engine and a Modified K&N Filter/Airbox. I felt that I could feel the difference. A couple of months ago, my brother wrecked his truck and got a 2000 Supercab 4.6l stock rental truck. So we decided to have a go at it. He pulled away from me off the line but when we stepped on it at 50mph, I pulled away from him. Is it possible that the rental truck has better gears in it? Is there a way that I can tell from looking at the rear end?

 

Do a search for "axle codes" and you should find several posts that explain the axle codes listed on the driver's door placard. No need to crawl around under the truck.

If you do want to get "down", there'll be a tag on the diff that lists the ratio. There are no "." on the tag, so a 3.55 ratio will be "3 55". If it has limited slip, the tag will read "3L55". The factory offers 3.08, 3.31, 3.55, or 3.73 ratios but not all ratios are available on all models.