Truck Spec's For Flatbed
 

If I'm going to be pulling heavy flatbed loads what type of spec's should i be looking for?? I asked about this truck once before but its possible i can pay cash for it.... here's the link to it 1994 PETERBILT 379EXHD Conventional Truck w/ Sleeper For Sale At TruckPaper.com

but i hear the argument that the 425 HP, 15speed, and 3.90 rears will make me suffer in the MPG department..i can deal with 5 mpg, would this really be a good buy for me around 15 K??

One issue I can see is I don't see any room in between the fuel tanks and tires for a tool box on each side. Also check for room for a headache rack (on the frame rails).

Who said you need a toolbox on the power unit?Most important is the trailer and I am sure he will have one on there.
Let's see, you started posting in 2008 and you have enough posts that tells me you are on here a lot.New to owner opeartorship huh?Do you wanna ride making money or do just like the Pete and its' CAT power.You should know by now that that set up will not get you less than 30% in fuel costs.My FLD and Columbia(one flat and the other stepdeck) gets well less than 27% of the gross in fuel cost.You should also know that truck is over priced for the year.1994 yr model should have over 900k ecm miles and they want what????????????$15000?
I bought my 03 Columbia way less than what they are asking.Even with an inframe that Pete is too much.NO, YOU WILL NOT MAKE ENOUGH MONEY IN THIS DAY AND AGE WITH 5MPG.

my dad has a 94 t800, flat top, 3406b, straight 9 speed, 4.11's, 24.5's pulling a box he gets 5-5.5mpg.

just trying to give some insite.

ok, now I understand the pm. I didn't see this thread before I checked my box. I have an 84 Pete 359 w/ a 3406b Cat, 18sp, 3.90 rears. I can get 6 mpg out of it IF I keep my foot out of it. I'm not speed demon so that's not a problem. I must admit I haven't checked my mpg by hand since I had it rebuilt, I've been strategically buying fuel.

There's a couple on another forum that have 359 Pete with a 700hp Cat that can get 7mpg . Next time I build mine I would like to build it to 6-700 hp, I didn't have enough funds this time around. I did ask my mechanic about getting that mpg out of a 700 hp CAT and he thought it was very probable.

Does it have a recent inframe? Most of the tires look good, new brakes all the way around? See what the frame looks like, did he just paint over rust or is it clean. I'd have to see in person to decide if 15,000 was a good price for it.

Also, how many miles on trans and rears. Make sure they have maintenance history as well.

Keep us posted.

it has an overhaul on it that has 660 K on it.. Has New Radiator.. New King Pin..New Rods and Bushing, New Brakes and New Clutch.. The Frame and Body has 1.3 mill on it.....

In the OP, he was talking heavy flatbed loads so I'm not sure fuel mileage would be my biggest concern. I think you'd need a minimum of 3.90 rear with that HP. Things about that truck that would make me keep looking are;
1. 425 HP might not be enough depending on weight and terrain.
2. I might consider a cabover with a 200 ish wheel base + a 53' trailer.

Just my two.

It has tall rubber which probably spins at 475 revs per mile, so your RPM at 60 MPH will be: 475 x 3.90 x 0.73 = 1,352 RPM. At 65 MPH, you'd be at 1352 / 60 x 65 = 1465 RPM, which is too high. But if you cruise between 60 and 62 MPH, there's no reason not to get at least 6 MPG.

A 3406b is good for roughly 500k miles before needing an overhaul. I don't know if the C model is much different or not but I'll ask my mechanic this morning. I would think though that you're close to an inframe. I just inframed mine for $13,500. That included a new radiator core. It was probably around 12k without the core and labor for the core.

New king pins is a plus as is the clutch.

Maybe offer 13k and see what he says.

Don't offer more than 10 grand. When you say "heavy flatbed work" How heavy is it? Those old motors can rev without losing fuel mileage. A lot were geared and setup to run 65 mph @15/1600 rpms. Theres no reason you won't get 6 mpg if you are grossing 80,000 or less. At 660k it could last to a million or it could go tommorrow so I'd lowball him as much as possible. On the bright side the 3406C is probably the best mechanical engine out there. I had a 88 K-W T600 with a 425 CAT/8LL/4.11 on short rubber doing tandem flatbed work. It ran 1700@65mph and got 7 mpg on flat ground and 6.5 in hilly terrain. Grossing 137,000lbs it got 6. Good luck.