Can Someone Please Decode these Vin's for me?

The first digit is country of origin. 1 is the U.S., then the ## means freightliner, the next 5 characters the model or line, series, chassis, cab type, engine type, brake system and gvwr. The ninth character is for security and the tenth is the model year. 11-17 identify the plant and assign a serial number for the sequence it came off the assembly line.

For the rear end type and ratio you need the tag identifyers usually found on the chunk. Usually a metal tag with etched or raised letters and numbers.

 

if you aren't near the truck , i would think any dealership should be able to tell you what it had from the factory. best way is the tag on the chunk though. johnny

 

The tag should be on the differential housing cover. The dealer wouldn't know without that # because there are several options.

If one is desperate like a lost tag, one can hang a piece of tape or string from the driveshaft and turn the wheel one full turn. Then count and guessdamate the partial turn.

 

That's a Rockwell. I'll do some searching.

 

Have you thought about just swapping the whole axle assy out. Many junk yards cut the rear frame off and sell them for around $2000.

You go to changing gears, you have to mic and shim which is a tedious job.

I found several 3.70



Here's one place that has a 3.73 for it. Yours is the 145 series.

http://www.worldamerican.com/pages/hd_diff.html

 

Some 3.58's

http://www.heavytruckparts.net/search.php?qsearch=TRUE&ManufMake=ROCKWELL&Model=RP20145&PartID=4440

 

3.73

http://www.truckpartsinventory.com/index.aspx?val=c22_m2_l7865

 

Here's another that has the ring and pinion

http://www.worlddrivetrainsupply.com/rockwell_differential-parts.html