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I intend to build this truck for cross country expedition, 4 wheeling, hunting etc. I am more interested in reliability, then a great powerhouse, although I would like to be able to haul reasonably heavy loads and not feel as if I am putting my vehicle through the ringer.
Common things to be on the lookout for?
-Yeti
For an expedition type vehicle i think a 1009 body style with 1008 running gear would be better, but to each their own. (im building a blazer based vehicle, so im a little biased)
From my point of view the non turbo 6.2 and 6.5 are pretty much the perfect motor for this type of use. They are a low compression mechanical diesel that is simple to fix and requires little maintenance. They dont have much power, but they get good mileage and you can run all sorts of crap through them and she'll keep on purring. Its not a race car, nor a high dollar cross country tow rig so dont expect to be pulling a 28k lb trailer out of Salt Lake city. for this kind of use i find the power to be plenty, only lacking in rare situations. they have been around a while and most junkyards the world over have a motor or two that you can rob parts off of if you are into that kind of thing.
So lets say you buy a 1008 or 1028 and want to run it all over gods green earth and dont want to get stranded in the middle of your adventure.
1. depending on mileage, replace the IP. While not cheap, they are the only real show stopper under the hood. If yours goes bad, you're not fixing it with a roll of duct tape and bailing wire and good luck finding one local.
2. replace the glow plugs.
3. ditch the auto glow plug controller and install a manual switch.
4. do a disc conversion on the rear end and replace the master cylinder with a unit from a V30 4 wheel disc van.
5. replace the front hubs with warn premium hubs.
6. While you are at it, rebuild the front knuckles and replace wheel bearings. I guarantee they'll show damage from water ingress if you are in the midwest. Replace the stock Dana 60 bearing retainer nuts with the 14 bolt style. the inner shaft seal and bearing are going to be junk from water getting in there, it is a crappy design so brace yourself to spend $20 and a few hours of your time to replace them. If you dont replace these you will be wearing the outer diameter of the outer stub shaft and allowing more water and junk in your wheel bearings as time goes on. you can do the math on what happens next.
7. install a DIY 2 micron fuel filter setup. Google it, and if you are interested i can provide more details with part numbers, pretty pictures and all that.
8. get some real tires. Id suggest 30-32" diameter with no lift.
that should provide you with a pretty stout expedition vehicle. from here there are lots of other goodies you can do, but the dollar/benefit ratio starts dropping off.
you can do all sorts of suspension mods if you need a vehicle with more flex or lift but dont fall in the trap of adding stuff you dont need for your intended use. Road manners will suffer significantly and i doubt you are going to trailer it when you go on a trip.
If you want to spend money on the motor dont bother with what is under the hood. Keep your eye out for a later 6.2 or 6.5 non turbo motor with a serpentine belt setup. I could go on and on as to why, but thats what your good friend google is for.
On the new motor you can install a girdle kit, ARP head studs, timing gears and a Fluidamper and it should last you long enough to put it in your will. Like i said before, the cost/benefit ratio gets hard to justify at this point but hopefully you are still single. while you can do these mods to a early motor, you might as well get the better cooling, heads, block casting, and less parasitic loss of the serp belt while you are at it.
While the TH400 trans is strong you will not be enjoying the 3 speeds if you have long trips in mind. These trucks have pretty low gears and 55 is about as fast as you'll want to go.
A 700R4 is a (pretty much) direct bolt in or you could find a early 4L80e, but you will need a $1000 controller for it. the 4L80 is stronger than a 700, but for the added cost.... its hard to justify especially since the 700 will drop in as-is.
Both these trannys have 4 speeds and a lock up converter making highway miles float by.
Gears. As mentioned by others they have 4.56 gears. Depending on what size tires and transmission you are going to end up with you might consider changing ratio. If you change gears you also might want to consider a stronger locking diff unit while you are in there. Expect to spend just shy of $1000 for a ARB, Eaton or whatnot.
the transfer case is going to be a NP208 and strong enough for "normal people". If you dont fall into that classification then you better get ready to shell out some serious coin.
You could get a NP205 and that is plenty strong, but their low range is overly high for anything other than bombing through the snow and moderate off roadeing. From here you could get a LowMax kit for the 205 or buy a Atlas transfer case. Both options are about the same in cost and final product. Or you could do what is called a doubler, where you put a transfer case in front of a stock 205 and bolt the two together but i personally dont like this idea for an expedition type vehicle.
you might want to consider some type of roll bar as well. the cabs on these trucks are not the strongest thing in the world and i for one would not trust my life in one without it if you are going to be back in possibly sticky situations.
A winch is also something you might want to consider. This is personal preference, but when i am going it alone i want to make sure i can get back home. A receiver type mount is handy, then you can put it on the front or back depending on how stupid (err, i mean stuck) you just got.
Id also suggest some FRP grating for who knows what. It stows well and is a real life saver for all sorts of situations you never thought you would be in.
thats about it for now, im tired of typing.