On that note- you're gonna want to AVOID any 4bt in a generator application, as the injector pump will not work for a OTR (over the road) application. The injection pump on the gens. was meant to pick up a load and adjust the idle accordingly.
I got my 4bt from a Ford chassis. The differences in the Ford/Chevy apps. are as follows (not all-inclusive, and not set in stone, but this is what I have seen):
1: The Ford's usually have a T-19 4 spd
2:The Chev's usually have an auto (turbo 400 I think)
3:The Ford's have an exhaust manifold that puts the turbo to the rear, mounted low (down).
4: The Chevy's mount theirs center and high (up).
5: The older (not sure of cut-off year) 4bt's have a rotory injection pump.
6:The newer (years??) 4bt's use an inline injection pump. (look at a 24v Cummins and you'll see an example of an inline pump).
7:Most Ford's do not use a power steering pump.
8:Alot of Chevy's do use a p-steering pump (this is important, as they are hard, not impossible to find- IF you do not live on the East coast -I know, weird...)
9:The Ford's use a vaccuum pump (driven off of the belts) to power the brake booster.
10: Most Chevy's have the desirable 'biscuit style' engine mounts. These mounts are fluid filled and really dampen out the 4bt's vibes. (think older Volvo style mounts)
11: Some Chevy versions are after-cooled. This is really easy to spot. On top of the driver's side of the engine, over the intake manifold, there is a long, tall box the tubo dumps it's charged air into.
12: Most Ford's use a vertical style oil filter. (It is almost exactly like the regular 6bt in Dodge trucks)
13: The majority of Chevy's use a verticle oil filter mount (messier @ oil change time)
Keep in mind:
The 4bt/6bt's are 'modular', as stated previously. That said, you are liable to run into a mix/match in anything.
In addition to E-bay, look at Craigslist. I got my whole truck for $1,900.00. I was able to sell the aluminum body as scrap for $1,000, the steel frame for $200, and the rear axle for $100. So, my 4bt, T-19 and wiring harness ended up costing me $600.00.
BEFORE you buy check:
The engine!! There are ALOT of crapped out Cummins out there ppl. are trying to sell. I have seen many that aren't worth the steel they are cast from.
A seller will tell you that these engines are 'bullet proof' or 'indestructible'. As any one knows, if it moves, it will wear out. Generally, these Cummins will last many 100's of thousands of miles, with the proper mait.
After 250k-ish you should check it for (let it warm up first...):
-Smoke from the turbo-a little black under power and throttle blips is normal. Spewing black indicates the turbo is shot. White smoke=engine needs attention. Probably the head gasket is gone (destroyed).
Always check for the normal-Oil leakes- these motors are usually ALWAYS filthy. You are looking for fresh oil, or dripping oil.
Nefarious rattles- it's a diesel, so it's gonna rattle. A rod knock or faulty injector is pretty easy to spot.
Let the engine get up to op. temp. with a squirt bottle, spray the exhaust manifold, near to where it meets the head. Don't soak it, it may crack. You are looking for a 'cool' exhaust port. If the water doesn't evap. as quickly on one port, likely a cylinder is dead, or the valve(s) is/are dead.
ALL Cummins use THE SAME SAE fly wheel pattern on the block. ALL OTR apps. use adapters to allow the use of Ford/Chevy/Dodge trannies (this doesn't include machinery or generators-likely they have some kind of SAE transmission). Use this to your advantage when re-powering your ride. Keep in mind the starter/input shaft/clutch req'ts.
Diesel autos and gas autos use different torque converters and valve bodies.
These engines were meant as medium duty industrial engines-that means maintenance is pretty easy, and you can even rebuild the engine in the vehicle. Replacement parts are pretty easy to come by.
Not ALL 6bt/4bt parts are interchangable.
-the oil cooler on the 6bt is too efficent for the 4bt
-only the injectors from the 1st generation- I think '89-'92 12valve's- will fit the 4bt.
-the turbo's are interchangable, but you need to know what you are doing-a bigger turbo DOES NOT EQUAL MORE POWER!!
-in diesels, the more fuel you give it, the more power you get. BUT it must be balanced with more air.
-EGT's/oil level/quality. Exhaust gas temperatures (EGT's) and the engine oil are the life and death of any diesel. Get an EGT gauge. For safety's sake, I wouldn't exceed 1050-1100 deg. on a 4bt. The 6bt's can go higher. Aluminum melts at 1200 deg. sustained. -enough said- Oil--make sure you have enough, and the right quality. Diesels use the oil to help trap soot. If your oil breaks down, so do you.
-On the EGT issue. If you are having trouble keeping the EGT's down you can:
-increase air flow to the engine
-decrease fuel to the engine
-cool the airflow (intercooler, water/meth injection...)
-ensure your engine is tuned correctly (lean diesels run cool, rich diesels run hot)
FINALLY: I am not a diesel mechanic. These are simply tips/tricks/knowledge I have gathered in my travels. I absolutely LOVE Cummins and have devoted alot of time learning about these great engines! I am on my 3rd Cummins re-power. Take the above for what it's worth, if not, no biggie.
Also, diesel-holics (you KNOW who you are) if you see anything that is in error, please feel free to correct me- I am never to old to learn!!