56 Chev rear axle in a P-15

[OldDad67]

I just finished installing a 56 Chev rear axle in my 49 P-15. I'm going to use a T-5 out of an S-10 and I had the axle from another project. I can't believe how close it fit. Same width and all I had to do was widen out the holes in the spring perches about 3/16 of an inch. Now I will have an E-brake and 3:70 gears, and my flattie 6. Should make a good summertime cruiser. Just thought you'd like to see. I also had my stock rear springs taken apart and had Teflon inserts put in and I'm using stock 48 shocks from Napa that are gas filled. I'm hoping it will improve the ride for an old fat guy.

[55 Fargo]

Deleted post to this thread

Edited March 8, 2012 by Rockwood

[Ed Griffin]

I think thats the same rear axle on my 50 Chebbie truck. Sure looks like it. I've been curious which one was used to replace the original and your post pretty well shows it. Did all of these come with the 3:70 gears? This one is connected to a TH400 automatic tranny and a 1957 283. It has great torque on take off but does wind out pretty much around 55 to 60mph. It may do better now that the carb. wont stutter on me at top end. Just have to get back on the road to see.

[OldDad67]

I think thats the same rear axle on my 50 Chebbie truck. Sure looks like it. I've been curious which one was used to replace the original and your post pretty well shows it. Did all of these come with the 3:70 gears? This one is connected to a TH400 automatic tranny and a 1957 283. It has great torque on take off but does wind out pretty much around 55 to 60mph. It may do better now that the carb. wont stutter on me at top end. Just have to get back on the road to see.

No it's not the same as a 50 Chevy truck, it is the same as all 55 and 56 passenger cars. The manual trans cars came with the 3:70 ratio and the auto's came with a 3:55, and overdrives came with 4:11. I wasn't sure how close it was to the P-15 but it's almost a bolt in.

[Ed Griffin]

No it's not the same as a 50 Chevy truck, it is the same as all 55 and 56 passenger cars. The manual trans cars came with the 3:70 ratio and the auto's came with a 3:55, and overdrives came with 4:11. I wasn't sure how close it was to the P-15 but it's almost a bolt in.

I'm sorry I wasnt clear to what I was saying. The rear axle on my truck had already been replaced. I had been curious as to what had replaced the original. The one you used looks like the one installed on my truck sometime later. I had looked around in the past to see if I could find one that looked like it but was unsuccessful. Now I know why because I was looking at later models, not 55/56. Thank you for the information on what ratio that went with what type transmission.

[Ed Griffin]

Here's the rear axle I was telling you about.

[OldDad67]

Here's the rear axle I was telling you about.

Ed the photo you sent didn't come through.

[OldDad67]

Here's the rear axle I was telling you about.

ED for some reason now the photo came through? Anyway that looks like a 57 Passenger car axle, notice the drain plug on the bottom of the housing. It was the only year with the plug. In 57 they went to 3:55 gears for the manual trans and 3:36 for the Auto. If you can give me the casting numbers on the lower front part of the case, and the stamped code on the upper left I might be able to tell you what the ratio is, assuming it hasn't been changed over the years.

[Ed Griffin]

ED for some reason now the photo came through? Anyway that looks like a 57 Passenger car axle, notice the drain plug on the bottom of the housing. It was the only year with the plug. In 57 they went to 3:55 gears for the manual trans and 3:36 for the Auto. If you can give me the casting numbers on the lower front part of the case, and the stamped code on the upper left I might be able to tell you what the ratio is, assuming it hasn't been changed over the years.

Yes I see what you mean by the drain plug on the bottom. Thank you for the offer. I hope this helps. These are all the numbers I copied off the rear end awhile back.

A3925 S GM h906 3725899

[OldDad67]

Ed were there some stamped numbers in the upper left hand corner. There sometimes hard to see, one thing for sure your 3 member with that number starting with 372 has to be a 57 or newer. But check for that stamped numer above.

[Ed Griffin]

I went out earlier looking for the stamped numbers by wire brushing the whole top area and never saw any thing. Then the bottom fell out of the sky and I had to scram. I came in, read your last post again and proceeded to beat my skull in for looking in the wrong spot. As soon as I can get back out there, weather permitting, I'll look at the upper left corner. If they are there I will find them. Thanks for trying to help, I really do appreciate it a lot. If I get this down to the correct info I think it will also help in finding the correct brake parts. I had a little trouble with this a couple yr's ago when working on them then.

[OldDad67]

In the top photo the casting number E167, translates to May16,1957, the bottom photo is those faint stamped markings that are hard to find the AB means it's out of an automatic trans car, an AA would mean a manual trans, the 5 means the month and the 23 is the day of the month.

[Ed Griffin]

Glad I rechecked these numbers and letters because I was off. If I understand you correctly this is what I have. The H306 means it's August 30th 1956 and the AB925 is Automatic September 25th.

When I checked around for the motors year it was also a 1956 made 283 though from what I understand the 283 didnt come out until 1957 so I'm wondering if this was early made but then issued in 57 for a car. I also hope with this info now we can figure out the ratio on the rear end. Please let me know if you need anything else and thank you very much for your help so far. It is much appreciated!

[OldDad67]

Glad I rechecked these numbers and letters because I was off. If I understand you correctly this is what I have. The H306 means it's August 30th 1956 and the AB925 is Automatic September 25th.

When I checked around for the motors year it was also a 1956 made 283 though from what I understand the 283 didnt come out until 1957 so I'm wondering if this was early made but then issued in 57 for a car. I also hope with this info now we can figure out the ratio on the rear end. Please let me know if you need anything else and thank you very much for your help so far. It is much appreciated!

I think you have the dates correct, 283's did come out in 57 but the new model year started in about Sept or October of 56 so the casting date would be correct. If the gears haven't been changed then you have a 3:36 automatic ratio. That's a nice gear for a cruiser.

[Ed Griffin]

Well I just wanted to thank you for all you did in helping me understand what this truck is equipped with. I wasn't even expecting to post anything about the rear until I saw the one you posted. Now I'm in the know. Thank you!

[OldDad67]

Your welcome Ed that's what makes this site so great, there are lots of people out there and lots of knowledge you can't find anywhere else. I learn something new everytime I sign on.