Trac Lock rear end
Posting Guru
Joined: Jul 2002
Posts: 1,335
Likes: 1
From: waco
That's an easy one.
Crawl up under the driver's side of the truck and look at the studs that hold the 3rd member in the axle housing. On one of those studs you will see a little metal tag. Scrape off the grease and grime and you will see numbers and letters. The tag will be aproximately 1" X 3". There will be 2 rows of numbers. Look at the bottom row nearest to the stud. The first section of numbers will tell you 2 things. (1) the gear ratio of the 3rd member (2) and whthere it is traction loc or not. For example....if your looking at a tag for a 3.25 gear set that is an open differential, it will read: 3.25. If your looking at that same tag and it is a traction loc rear axle, it will read: 3L25. A (.) is open, and an (L) is traction loc.
Doc
Crawl up under the driver's side of the truck and look at the studs that hold the 3rd member in the axle housing. On one of those studs you will see a little metal tag. Scrape off the grease and grime and you will see numbers and letters. The tag will be aproximately 1" X 3". There will be 2 rows of numbers. Look at the bottom row nearest to the stud. The first section of numbers will tell you 2 things. (1) the gear ratio of the 3rd member (2) and whthere it is traction loc or not. For example....if your looking at a tag for a 3.25 gear set that is an open differential, it will read: 3.25. If your looking at that same tag and it is a traction loc rear axle, it will read: 3L25. A (.) is open, and an (L) is traction loc.
Doc
Posting Guru
Joined: Sep 2003
Posts: 1,192
Likes: 1
From: lino lakes, mn
traction loc is a for trade name just jack up the rear end spin the wheels if they both go the same wat its got trac.locf if they spin oppisit ways its open if your still in dought hold one wheel spin the other if it spins its an mopen diff if itr doesn't its a locked unit
trac-loc = Ford , positraction =Chrysler corp , limited slip = GM all the same thing
trac-loc = Ford , positraction =Chrysler corp , limited slip = GM all the same thing
Trending Topics
Laughing Gas
Joined: Aug 2004
Posts: 1,249
Likes: 2
From: Rockport, WA
I think the Dana Spicer trade name is Powr-Lok. Right?
My 1977 F250 is supposed to have a locker, by the number on the door plate. But it acts like an open differential; if you step on it on grass, one wheel spins.
My 1977 F250 is supposed to have a locker, by the number on the door plate. But it acts like an open differential; if you step on it on grass, one wheel spins.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Fleet Mechanic
Joined: Feb 2002
Posts: 1,483
Likes: 273
From: Tulare U.S.A.
Dana Spicer list their L.S. as Trac-Loc (the cheaper version) and Powr-Loc (the more expensive version). That is their name not Fords. The difference in L.S. names is from the manufacture of the rear end not necessary the vehicle its in. For instance if you have a Dana spicer rear end in a Ford, Dodge, or Chevy the L.S. would either be a Trac-loc or a Powr-Loc. Most vehicles with Dana Spicer reareds came with the Trac-loc from the factory because they were cheaper. But I have seen some Powr-locs in heavy duty trucks from the factory.
Leadmic
Leadmic
New User
Joined: Jan 2008
Posts: 0
Likes: 24
Look on the rating plate on the door in the axle code area.
If it has an H# then it came with L/S.
The only other way is to either yank the diff out and see the locking part or count the splines on the gears & do the math.
Only certain gears got L/S.
If it has an H# then it came with L/S.
The only other way is to either yank the diff out and see the locking part or count the splines on the gears & do the math.
Only certain gears got L/S.
Laughing Gas
Joined: Aug 2004
Posts: 1,249
Likes: 2
From: Rockport, WA
With a rig as old as mine, "open it up and look" would be the most reliable approach. The door plate indicates it left the factory with limited slip of some sort, but it acts like an open diff. It may not be the original axle.
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
I have seen a lot of worn out locking diffs act like open diffs and I have even seen worn out open diffs act somewhat like a locker when the spiders bind up. It is difficult to tell without an inspection or a tag.
Laughing Gas
Joined: Aug 2004
Posts: 1,249
Likes: 2
From: Rockport, WA
That's logical advice. I bought a gasket, and have been planning to order some Redline 75-90 gear oil and make a change. Just haven't gotten around to it. Once it's off the ground in the shop, it will be easy to sort things out.
Senior User
Joined: Sep 2003
Posts: 364
Likes: 0
From: Hartland, MI
The only diff between Powr-Loc and Trac-Loc is the case design. Powr-Loc's are two peice bolted together and Trac-Loc's are one peice cases. I just bought and installed new guts in my 1977 F-250 Trac-Loc differential. You can still get the internal guts from Dana for about $155 at drivetrain.com for 30 spline axles as in a 77 F-250 2wd