The Stovebolt Site Forums The Parking Lot Tons 'o Fun 4:10 HO72 gear swap for 1950 3800

I scored a 1969 4:10 NOS gear set, got a later pinion bearing retainer, NOS front and rear pinion bearings. What do I need to know about swapping to later gears? Should all this just be a bolt-in job or am I missing anything?

You will need some bushing and bearing drivers, a few large brass drifts and a steady hand with a hammer. You will also need the correct shims to set your pinion depth. Do the new gears have bearings on them? What was your old ratio? If it was 5.14 I may be interested in purchasing them. I also see you are in Virginia? Where abouts? I am in the Virginia Beach area.

Got all that, except for shims. No bearings on the pinion, got those NOS too. Also scored NOS spider, spider gears, and side gears. I'm in Afton where I-64 goes over the mountain. I'll probably keep the 5:14 gear set, at least for now.

You can get a pinion shim kit from Randy's Ring and pinion I believe. I can help you set it up if you feel like making the trip one weekend. I have everything in my shop to make it happen. I'll be traveling through your area a few times over the next few weekends as well if you need anything else. I will be traveling for work though so won't have much time to "stop" by. If you change your mind on the 5.14 set let me know. I have 4.56 gear sets and can get more 4.10s if you are interested in those.

Got shims and a seal coming from Randy's. Do I need a gasket for the pinion retainer?

I just use ultra black RTV.

Instead of regular RTV permatex makes a sealant just for rearends in a green tube,any auto parts store should have it.

So besides being called a rear end on a regular basis, I don't know a whole lot about how the inner workings work. My question is from a swap in gear change, what are options for an easy swap from the current gears that are in my 1949 3800 dually? What vehicles/years am I looking for? Could I retain a granny gear similar speed, but get back up to a cruising highway speed above 40mph. Thoughts. Thanks

aggie john, the same rear end was used through 1972 in 3/4 & 1 ton trucks. 1 tons in the 50s usually had 5.14s. 3/4 tons with 6 cyl. usually had 4.57s. 67-72 3/4 tons with V8s (especially auto trans equipped) usually had 4.10s. if you find a 67-72 truck with 4.10 gears that's in good shape (& they usually are) & doesn't have to much slack, you can just swap in the whole 3rd member & not worry about setting up the gears. If you do happen to only come up with the ring & pinion gears, get a factory service manual for AD trucks & it gives step by step Instructions for disassembly & reassembly of the 3rd member. setting up r&p gears & rebuilding manual transmissions is not rocket science or some kind of black art. If you can do a brake job or rebuild a carb. you can do it. the only special tools needed are a dial indicator & you could make something for those oddball looking wrenches in the manual for adjusting the carrier bearings, or just use a hammer & punch for that.
I've just done this swap On my 50 3800 & love it. I run 60 & 65 on the highway no problem. granny low can't tell the difference, it'll still practically climb a tree @ idle!

And if you need something after trying out the 410/1 for driving the interstates you can have a rear-end built that will give you 342/1 as I did for my 1948 3804. I was not happy with the 410/1 at all I wanted the truck to cruz the highway at traffic flow speeds. The change from the 514/1 to 410/1 was good but.

I have changed both my '49 1 ton platform and '50 1 ton panel by changing the pumpkin assembly to a '72 4:10. It was very easy, strictly bolt in and only took about an hour and a half. With the GMC 248, I now can cruise happily at 65 MPH in the '49 platform. the '50 panel has .73 ranger overdrive with a modified 302 and has no problem doing 75 MPH all day.

Ok, so I managed to locate a 4.10 third member much faster and easier than I would have ever imagined. At any rate, now serves to ask another question that I would imagine someone has already researched and/or addressed....what to do about the speedometer? Is there an off the shelf speedo gear that can be purchased? Any way to get that corrected? Thanks

If I were doing it again, I would take it for a drive with a GPS and make note of how to scale the readings. Then you know what speed you are doing. Also, I understand that there are suppliers around that can make up an inline converter.

jim carters' sells speedo ratio adapters & so do several others. do a google search.
try this: http://www.transmissioncenter.net/speedometer_calibration_______va.htm#gm ratio adapter

Is the rear end containing the HO72 have the same round, domed rear pumpkin cover, or is it a little different cover (dana 60 perhaps)? I looked at one today that a guy had for sale. '71 3/4 ton, factory automatic, and it was not the same rear end cover as my 49. Told him I'd get back to him if it would work.

http://i422.photobucket.com/albums/pp303/jongersbach/Rear%20End/IMG_0700.jpg

Just want to double check myself before I pass on what would be a good deal for a rear end.

The photo looks like a Dana 60. No parts will work with your HO72. And yes, all the HO's have the round cover.

Thank you for confirming my feeling. Anybody need a Dana 60? The quest continues.....

Did you have custom gears made to get the 342/1? How did you do it?

So I may have found the rear end. I just want to confirm, as the cab and bed is not original. He told me that he bought it complete and was unable to get a title and scrapped the rest. It was a '72 3/4 ton, Cheyenne special, with a big block v8 and th400. He indicated it was all original. It has the round domed pumpkin just like my '49, and a coil spring rear end. Its half buried in the dirt, but I counted 10 bolts.

I guess before I lay down the cash for it I want to confirm with those who know much better than I whether or not it is the 4.10:1 that I seek. Link below to the photo of the picture:

http://i422.photobucket.com/albums/pp303/jongersbach/Rear%20End/IMG_0906.jpg

Thanks

Oh Yeah,
It,s definately a HO Series rear
question remains is it a HO 52 or a HO 72 pumpkin.
Cant tell from the pics.
Are the wheels/lugs an 8 pattern?
If they are it,s the right ham.
Now the question remains,what ratio is it.
Get the cast #,s off the case and get the stamped #,s off the Case.
Regards,
steve sr.

Steve, so if I get the #'s, what am I looking for? My studies show that both the HO52 and HO72 rear will work, correct? I pulled up the '72 manual and it stated that with the big v8 and auto tranny, it is either a 4.10 or a 3.54. I hope it is the 4.10, because the 3.54 I believe would swing to the opposite side from where I am currently with the 5.14. The 4.10 would be ideal.

NO that wont work!
I asked the question of HO 52 or HO 72 rear because of Lug patterns and tonnage.
HO 52 is 1/2 ton 6 lug bolt pattern since Christ was a Corporale till about 1972.
HO 72 is the style rear you need in a certain year,because you can pull your axle shafts and pop out the old ham, and then just Slide the axles back in.
regards,
steve sr.

I thought the HO52 was in 3/4 tons, and the HO72 in one tons? This rear end is a 3/4 ton, so it should work then, correct. Its a decent price, and the guy is pretty good to work with. I think if I help him to pull it, and it wasn't right, that he would work with me on finding one that does. I just want to be right before I go through the effort of pulling it.

You are correct. And the pumpkins are interchangeable.

Well, I will be picking up the whole rear end, so we shall see. Anyone else have any suggestions for things to have on hand for the swap or any tips/tricks to make the disassembly/reassembly easier.

Thanks

Picked up the rear end, and opened up the cover and counted ring gear teeth. 41 teeth. Couldn't get to the pinion to count, so I removed the 3rd member (gonna have to anyway) and still can't get to the pinion to count teeth. The 4 bolts that hold the pinion in place, if they are removed, and the yoke and pinion come out, do I have to set the gears back up?

Looked for stampings on the ring gear - found the following:
10:41 GM and 3 71. It is from a 71 chevy, so perhaps the 3 71 is a date stamping. Can anyone derive anything from the other stamping? Here's to hoping that it can be derived from that and that 10:41 translates into 4.10:1. Thanks

Is it possible that you miscounted? I think a 4.10:1 will have 41 teeth on the ring gear and 10 on the pinion.

Update. there are 41 teeth on the ring. This is what happens when an aggie trys to count!

So, would the 10:41 stamped on the ring gear give me the pinion/ring teeth count? 10 teeth on the pinion, 41 teeth on the ring gear....I guess I was looking at it as ring/pinion. They stamped it pinion/ring. Sometimes it helps to just stand back and draw it out.

So I just got lucky in the scrapyard and got my highway rear! Sweet. while i like driving 40 in my old truck, 55 may be better, and the motor will appreciate it as well!