New to this forum, and new to the Heavy truck world. I am looking for some info on how to identify my tranny and rear end. I am running a modified F600 extended crew cab with a 429 gas and a 5 speed manual trans. 1st gear is so dang low I don't use it, and 5th gear maxed out at 3500 rpm's is 65 mph. I have read some about the 2 speed rear end but don't know how to identify it. If it is not a 2 speed, then I would like to know what rear end it is so I can gear it up and achieve 80+ mph. I plan to fab a dove tail style utility bed so I can pull a 5th wheel camper.


I believe this started it's life as a delivery box van. Any ideas on how to soften up the ride? I'm thinking of a three or four link setup on the front axle with coil springs and air bags. Lose several of the leaves on the rear springs and add air bags to that as well.

 

The Eaton 2 speed rear axles that I'm familiar with have an electric motor attached to the front of the differential off to the left side of the pinion. They also have Low and Lower gear ratios as in 6.00:1 and 8.50:1 and there are no numerically lower (like 4.10:1) ring and pinions available. There should be an ID tag somewhere on the housing, either welded to the housing or attached under one of the nuts holding the differential in the housing.

The transmission should also have an ID tag attached to it, usually a metal plate attached under a nut somewhere.

F600's are not known for soft, smooth rides. I suppose you could rig up an air suspension system.

You might find the VIN of the original truck stamped into the top of the right front frame rail, usually right over the axle. That would help identify what type of truck it originally was.

 

I will look in depth this weekend. For now there are no visible tags bolted on the third member. Also no motor attached to the diff.

The title lists it as medium heavy for model and TCC for body type. It will definitely be getting a softer ride one way or another.

 

TRANS & AXLE codes printed on the Certification Label, glued to the left door face below the latch.

Post a pic of it.

 

It's a Frankenstein truck. This is the only sticker on the door.

 

12,850 GVWR with an 8000 GAWR for the rear axle is very low for an F600. That's more F350 territory.

80 MPH? Try a panic stop from 65 and ask yourself if you really want to run 80.

There have been a few posts recently about axles from the Freightliner MT45s and MT55s being a good swap in for these due to the higher gear ratios found in those, many in the 3.31-3.5x range. Many have disc brakes as well.

Due to CA emissions rules, a bunch of those are going to be on the market. The 2000 model I drive daily is awaiting replacement. Cummins and Allison in those as well.

For a smooth ride, air is your only option.

 

That's my Frankenstein reference. A VIN search tells me it's an F600G 7.0L straight truck with a standard cab. If that's the case, this truck is made of at least 3 different trucks. With the existing powertrain and chassis I guarantee it's much more than F350 GVRW. I haven't weighed it yet, but it must be at least 10K by it's self. I'll keep digging, looking for more numbers.

 

I thought you said the chassis came from a bread truck or some other delivery van and the pickup body was installed on it? You need to find a VIN on the frame in order to identify at least what the year model of the original truck was in order to narrow down the possibilities for transmission and rear axle choices. The VIN on the cab is meaningless if this is a re-body.

 

Thanks for the info guys.


I will be doing some serious cleaning of the underside this weekend looking for numbers. I'm really doing nothing more than guessing at what this began life as. There are a lot of things that don't add up just looking the thing over. The paint on the roof is cracked, chipped and pealing, so I'm going to sandblast that and check out the seams. I'll probably take out the trim and carpet also to get a better idea and make sure everything looks solid. I'll share more when I know more.