I've Got An 4x4 1988 Quad Cab F350 W/ 7.3 Idi. The Front Axle Is A Dana 60 But I Can't Figure Out The Gear Ratio. There Is No Id Tag On The Front Or Rear Axles Or The Doors, Ya Gotta Love Old Trucks, But There Is The Raised Numbers 620093r On The Front Axle. There Are Also Some Real Small Numbers On The Axle Tube Under 20 Years Of Grease I'm Still Trying To Read. Where Else Can I Find Numers To Id These Axle's Ratios. Also A Good Site For Front Axle Codes Would Be Awesome, I've Found One For Rear Axles But No Luck With Fronts.

 

This will get you started, but if tags have been removed from the axles then you are going to have to remve the covers and count teeth, or inspect the side of the gear to reveal the ratio.
Chances are that during some maintenance someone removed the tags, or perhaps over the years someone changed the ratio, and left the tags off since they no longer contained any accurate or valuable data.

This will provide you with any answers you may have.
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My best guess with the IDI is that it has 3.55 gears.

 

Im with cheeto on this one, the idi points me to 3.55 area.

If there are no tags, your best bet is to count teeth.

 

one way to check is jack up rear end and turn the tire one revolution and count the revolutions that the driveshaft turns per one tire revolution,this will get you in the ball park,3.5 complete turns of driveshaft to one tire revolution =3.55 and such

 

Alright I Found A Data Plate Screwed To The Firewall. It Has The Following Three Codes Stamped On It

2729pl59a12dhx
2h8a22coop6mvd
W36jcb394604w5mi

Any Ideas On Which Gives Me The Gear Ratio?

 

bwahahaha... nope. sorry, that looks like a jumble of letters and numbers to me.

What about in the door jamb? They usualy have a plate with the engine code, trans code, axle code, weight of the truck, weight limits of the truck... so forth and so on, well actually i dont know if they were on trucks from back then, actually come to think of it, i dont think my 69 had that plate either. So never mind scratch that.

 

12 bolts a few dollars in lube, and a tube of RTV.
Job is done in about 25 minutes, only because the RTV needs about 15 minutes to set before you can install the cover again.
Chances are the lube should be replaced anyway. When was the last time the inspection cover was removed, and the diff recieved a service?
If its like most, it has never been removed since 88. However, since the tags (front and rear) are gone, this is a pretty good indication that it has been apart at least once, and if the tags were purposely left off, because the ratio was changed, you will have to open the diff up regardless. Any factory part numbers may no longer be accurate.
One would think that after 20 years it deserves a little peek anyway. Nice to see what is goin on on there.
A little effort will take all of the guess work out of this, and on the bright side, your diffs will get some fresh lube.

 

I'm Gonna Pull This Axle Out To Put Under Another Truck, So I Want To Know If I'm Gonna Have To Switch Gears Before I Get Started. Thanks Though.

 

I Also Found The Numbers 610 313 2pj Stamped On The Axle Tube.