And we haven’t even gotten into pinion angle yet.
Lol
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front axle complete with the wheels (but I suppose that is obvious)
meh, that doesn’t matter, what’s important is the tires, and that they are the same outside diameter as the rears! 
or, you could change the gearing hahah!
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Here are some potentially relevant photos from Joe’s place up the road where he had several halftracks that retired from the logging industry around here. Food for thought
I’m not sure how long the wheeled conversion actually ran but, they went to some trouble to try and make it work
Assuming I’ve done my calculations right, I get the following figures:
The M2 HT front axle had a gear ratio of 6.8:1 and used 8.25-20 tires with a diameter of 38.25”, giving a circumference (diameter * PI) of 120.166” and a prop-shaft per-revolution travel distance (circumference/ratio) of 17.671”.
The CCKW axles had a gear ratio of 6.67:1 and used 7.5-20 tires with a diameter of 36.75”, giving a circumference (diameter * PI) of 115.453” and a prop-shaft per-revolution travel distance (circumference/ratio) of 17.309”
That means the front wheels would cover 0.362” more than the rears for each revolution of the prop shafts, and the output front & rear from the CCKW transfer box would be the same. So for every thirty-three prop-shaft revolutions the front wheels would cover a foot more ground than the rears! Definitely NOT suitable for 6x6 drive on anything other than very soft ground.
The sensible thing to do would be to replace the HT front axle & wheels with CCKW ones, but the pic says they didn’t do that!
Sources for the numbers:
Tire size info: http://www.usarmymodels.com/ARTICLES/Tires/US%20Tires.jpg
M2/M3 HT axle ratio info: Need a Halftrack expert - G503 Military Vehicle Message Forums
CCKW axle ratio info: https://forums.g503.com/viewtopic.php?t=263871
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Nick I too considered swaping in the front axle from a Deuce so gear ratios would match but the fact remains; as long as they are still running the larger diameter tires in front the 6x6 driveline in all wheel drive will quickly balk and shortly thereafter quickly break.
I still maintain that the need/desire here was for a quick armored cab cargo truck conversion so simply disconnecting the front drive shaft and making this a 4x6 vehicle would have been the quickest and easiest solution to building this conversion. And the most expedient.
p.s. Also I seriously doubt the hole patern and diameter of the half-track wheel rims would have allowed them to be mouned on the Deuce wheel hubs or vice veasa.
Tom. Sorry we put you to all that brain work. I never could have come up with all that amazing data.
I am just simply relying on 4 wheel driving experience and hopefully what is a practical backyard garage chop shop mentality.
So it would be ideal for Tunisia circa 1944 or am misjudging the location/conditions?
Tunisia has a lot of hard ground as well as sand dunes
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It might be OK off-road on loose sand, but as soon as you hit a hardened road surface (even compacted dirt) you’d need to disengage the front axle. And on firm off-road ground you wouldn’t use it either. As others have stated here, I suspect they just used it as a 6x4 truck, with the option for extra pull if stuck in a ditch etc - assuming they even bothered to connect the front prop shaft at all.
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That would simplify things, no.
I chose to connect the front drive on my model knowing full well it would only be usuable in extreme situations if at all.
Hi Mike-
Well, yes - the fun of swapping truck parts for conversions and conversation!
I think we are basically on the same page here, as my thoughts include the choice of disconnecting the front driveshaft - an easy fix.
But - if you did want a functional 6x6, I’d still go with either: 1) changing out the front axle with that from a 6x6 truck (with gears to match in the back); or 2) keeping the front axle from the halftrack, and changing its ring an pinion gears to match those in the rear end, from the donor (6x6) truck.
I think this because in relative terms, the size difference between the front and rear tires might be small, when compared with the difference between axle ratios, like 6,7, or 8 to 1 in the front, and 3 or 4 to 1 in the rear (as I understand it , the front axle of the halftrack is geared between 6 and 8 to 1, whereas the 6x6 might be geared somewhere in the high threes to high fours to 1) which would be significant.
That difference in gearing would likely cause problems for the drivetrain, even in slick terrain.
Think about even a normal 4x4 with 3.73:1 gears in the front and 4.56:1 gears in the back, with the same dia tires - that would be a mess, would be a PITA to drive, and would eat the transfer case and U-joints.
Whereas, if you have 3.73:1 front and back gears with different front and rear diameter tires (within reason - say 30" and 32") - it would also be a PITA to drive- but, would work, particularly in the scenario you describe - I’d rather have some tire spin/skip than gears grinding.
Ask me how I know this bit of trivia?? You too can explore this scenario when out four wheeling with friends, and say, you blow a 32" tire…and your spare is a smaller 30" diameter 
…and your buddies spares are also smaller diameter 
- yes, you can limp home that way, which is important if you actually need 4x4 to get out.
Essentially the same as what happens if you blow a tire in a sassy new AWD car - the car rims/tires might be huge - 18/20"+ dia, but the spare tires are always (OK, I suppose some mfgr might include a big spare, but I doubt too many do - as they take up a lot of room to store) very small, for temporary use - again, not ideal, but you won’t ruin the driveline, and you will get home.
I went back and looked at the old photo, above, and it describes the “front being from and M2 or M3”, and goes on to note that “tech details are not known”. Another thought here - we have no idea how successful this conversion was, and as we don’t see too many other conversions like this - maybe it was a big flop? or just more work than it was worth - who knows?
My bet - they disconnected the driveshaft.
Happy four wheelin’
Cheers
Nick
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Ya Nick, I often wonder about these poor little four wheel drive fellers who have four big tires on their jeep but are still carrying the factory spare on the back???
As to talking about changing gear ratios or ring and pinions. Yes, if this were stateside and in a factory environment then anything is possible. But here we are talking about a one-off, battle field expedient. I imagine the Master Sargent in charge of the Motor Facility told the Commander he could do it in 3 days with 3 guys and the plan got approved because they were having a sniper problem and needed an armored cargo truck. This would have had to be done quickly and with readily available repaired or junk parts that they had on hand.
And since this conversion conversation (conjunction junction?) has gone on for so long I am going to go ahead and show my version of this same model vehicle from a few years ago. I still have not gotten around to adding decals.
A Deuce and a Half or a just Half a Deuce:
Here we see the proud M/Sgt. posing with his brain child.
The Deuce still has its’ regular spare mounted under the chassis as SOP but I threw a drilled out half-track spare in the load box just in case of an emergency. The wartime combat half-tracks usually ran on SOLID RUBBER TIRES so a spare probably really wasn’t very necessary in this case.
Just as a personal challenge I put myself under the same time constraints as I felt the Motor Pool guys were under and built this model in less than 48 hours. I tried to pull an all-nighter and do it in 24 but by 3am I gave out.
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Are we sure it isn’t a halftrack cab put on a truck chassis?
There may be changes necessary to add larger wheels, but would that be easier? The bumper on the armored truck looks very similar to that on the CCKW to the right.
KL
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Kurt, I think not. Simply because if that were the case, they would have gone with the front wheels from the Deuce and avoided entirely the problem of different wheel diameters and then had a fully functional armored 6x6.
As to bumpers, that is just a matter of drilling four new mounting holes to match the frame spacing and bolting it onto the existing frame mounts. On my version of the truck I chose to use the heavier WC bumper rather than the smaller (non-winch) half-track bumper as seen in the photo of the real thing.
I agree with Mike - why put the bigger wheels on if the front axle came from a CCKW? Sure the 20" rim should fit, but they musta known the different size would be a problem?
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