[63GMCKid]

Originally Posted by 350TacoZilla

Amazing work man! I had a 305v6 63 gmc stepside 4x4 and always hope to get another one (if I ever do it is going to be 478V6 4spd truck lol). I was wondering if you dont want a lift block in rear why not do a shackle flip like alot or us 73-87 guys do, you could make the rear mount yourself and I think the trucks ride bit better like that.

Thanks!

I decided against a shackle flip because this truck will be used to tow stuff that I can't with my daily driver (1990 2wd 1500 Suburban), like my tractor or anything else too heavy for my 'Burb. Shackle flips are known to be iffy for towing if not set up right. Not to say that a compression shackle is bad, a lot of the later dodge trucks (like 3rd gen and up I guess?) use a compression shackle, but they are set up for it from the factory, and the angle of the shackle has a lot to do with that too (again, they are set up right from the factory). The problem with towing with a truck that has a shackle flip with a shackle angle that is accepted as correct to the off road crowd (generally something like 30* back) is that the weight of the truck is forcing the shackle to move and flatten the spring, it makes it feel very spongy/flexy, that's why it works good offroad, bad when towing, any extra weight just applies more leverage to the shackle to flatten out the spring. In a tension shackle, the weight of the truck is naturally trying to keep the shackle vertical because its pulling down and forward on the shackle against the spring, so it doesn't get spongy with more weight, making it safer for towing.

Originally Posted by Captainfab

I know the 1/2 ton Napco's used the same Eaton HO32 third member, and what appeared to be essentially the same housing as the rear. Of course the center was offset to the pass side. I would imagine the 3/4 tons would have used the Eaton HO52/72 on the front in the same way.

Originally Posted by jbclassix

Hey man, seems like a lot of threads on pirate and other 4x4 boards say the tubes can't take the stress as a front. I really hope that's not true! I have a HO52 waiting to become a front once i get to that point. Didn't Napco use Eatons up front?
Posted via Mobile Device

I'm curious as to where you saw this on Pirate, do you have a link? I recently posted in a thread there about someone asking about the strength of an original Napco Eaton front axle, but the strength of the tubes was not an issue that was brought up, nor have I seen that mentioned in the Eaton thread on Pirate. I know the Eaton tubes are only 5/16'' wall thickness, but something to keep in mind is that an all steel housing is basically "self trussing" by design. If I were running a Cummins or all iron big block or one of the old V6's in my GMC, I would possibly have a slight concern about bending the housing, but I'm not running any of those so I'm not too worried about it at this point. The previous owner had an all iron big block in it with a 10 bolt front (All stock other than that though, the truck never had anything larger than 31's on it) for many years and I've still got that 10 bolt and its not bent. I may do a simple light weight plate and tube truss if I feel that it's not going to be strong enough.

And yes, the Napco 4x4 conversion trucks of the 50's had a Napco Eaton front axle. I know for the 3/4 tons they used the HO52/72 diff, with closed knuckles and Rzeppa joints (Similar to a Birfield/CV) and they had the diff on the passenger side.

EDIT: I've seen it mentioned on Pirate that 14BFF tubes are weak and bend easily and more so in a front application, but never seen any mention of that for an Eaton front. There is a guy on Pirate who used a Napco Eaton front axle in his build, did a cut and turn, and a rebuild, and I don't remember reading anything about him being concerned about the tube strength. As far as I know, I'm the only one on Pirate who has built an Eaton front using as much of the original tubes as possible, the other guy that is building an Eaton/60 front used D60 tubes welded to just the center section of the Eaton housing, and I don't believe he is finished yet. Really we are in uncharted territory with the Eaton front axles because the Napco front axles are so rare and myself and 1 other guy so far are the only ones I know of to build an Eaton/60, so it's really more of an experiment at this stage, it's not proven like a 14b front which has been done hundreds of times before. If you are planning on building one, I would dive right into it, go at it however you think it should be done. There is no right way or wrong way at this stage, my Eaton front is built in a much different way than the other one on Pirate, either way is good if care is taken to make everything turns out right without cutting corners. I just did what worked best for me with the tools (and budget) I had available.