M998 vs M1123 just chassis differences?

[hotrdd]

Looking at doing a custom build with a Duramax engine and Allison transmission. As such we are looking at purchasing a HUMVEE frame. Right now we have a good rolling M998 available that doesn’t have an engine or transmission. But I keep reading that I shouldn’t waste my money on a M998 and instead go for an M1123, because it is more heavy duty and can carry more weight. BUT if you take away the engine and transmission are the core chassis and axle / portal axles any different?

 

[Coug]

The M1123 is identical to the M998A2 for almost everything. Marines wanted the truck without the rear bumper and to have the deep water fording stuff already installed.

The M998 or M998A1 is a different frame part number than the A2 trucks.

So depending if the M998 rolling chassis is an A0 or A1 frame, then everything on it is lighter duty than the later A2 chassis. halfshafts have lower ratings, transfer case is an NP218 vs NP242. Might even still have the parking brake on the driveshaft instead of the brake calipers if you're unlucky.

 

[hotrdd]

But if I am replacing the motor, transmission and transfer case will the early M998 A0 still be good enough. 1/2 shafts can easily be upgraded., or at least I assume I can upgrade them later?

 

[Coug]

But if I am replacing the motor, transmission and transfer case will the early M998 A0 still be good enough. 1/2 shafts can easily be upgraded., or at least I assume I can upgrade them later?

Yes, you can upgrade them later. You need the shafts and the hub input gear, as the shafts use a different size spline into the hub.

Any truck will be good enough, if you want to dump the money into it.

Spring mounts, springs, ball joints, steering components, and lots of other little stuff got upgraded between the A0/A1 and the A2 versions as well.
I've also seen some frame strengthening plates available but can't remember if they were part of an MWO or something.

A2 or newer would be better if you're planning on putting in a high power drivetrain, but no reason why you can't do whatever you want with an earlier chassis.

 

[Mogman]

My Duravee is an A0, what would make a difference is if you wanted to build a "hot rod" which the A0 in fine or a heavy hauler in which you would start with an A2.
What model Duramax and transfer case are you starting with?
Edit, you do not want to start with a later truck with the 3.07 gears, 2.56 (A0) is best, 2.73 is OK

 

[hotrdd]

Working on getting the humvee first and then will sort out the engine, transmission and transfer case combo. I'm a realist and realize my humvee will spend 90% of its travel on asphalt so it needs to be setup to go down the HWY.