I have a 1956 Chevy 3100 pickup project. I discovered just this weekend that my cab is a 58-59 when I was trying to mount the hood hinges. The firewall holes are vertically too far apart. I did some research and found that the hinges for a 58-59 truck are different. So I thought maybe I had the wrong hinges. I found someone selling a set of 55-57 hinges and compared them to mine, and they were exactly the same. He has a 58 pickup and has the appropriate hinges (he made the same mistake, but in reverse, so he's selling the incorrect hinges). So we compared the hinges and the 58-59 hinge has hood mount holes and firewall mount holes that are farther apart from each other. So I got to thinking about it and realized that was probably why the battery tray I bought didn't fit. The firewall holes for the tray were too far apart horizontally by about 1/2 inch. I know the front clip is entirely different, and the frame is longer in the front on the 58-59. This build is not to original, so I am not overly concerned about the cab being the wrong year. 1. Does anyone know of any other differences between the 55-57 cab and the 58-59 cab? 2. Considering die-grinding the hinge holes to make them longer to fit the firewall mounts. Will I have problems aligning my 56 hood if I do this? 3. The 58-59 hinge will fit the firewall, but can it be drilled to fit the hood mounting holes? Then there is the spring issue being it mounts to the inner fender well. 3. I am also considering relocating the lower hinge mount hole in the firewall, but don't know if the upper hole is in the same location between both cabs. Anyone know?
Here is my truck, in case you were interested. This is how I bought it in December 2015, except I have added the wheels and tires. Trying to rewire it and get it road worthy to start.
I am not sure on all the differences but I do know the hinge mounting and hinges are different for a 58/59. Squirrel may comment on this thread which could help. Another good source is the forum for Chevy trucks. I think it's listed for 67-72 but it covers back to '47's and is divided into design styles. This falls under the "Task Force". Good source of info.
That sums it up for the differences, other than the wiper assembly and transmissions. Find a template and mounting positions on the firewall, drill, weld a nut on the backside and go from there. There is not an easy way out of this, you will just need to rig it to work. Have someone here take some measurements for you and have at it.
58-59 electric wiper motors wont fit in a 55-57 cab. the door striker bolts on a 59 are bigger. I think the rest if it is covered by others. The upper hood hinge hole is in the same place. Use hinges that match the year of the front sheetmetal. The front sheet metal is all completely different between 57 and 58. Also the outer front sheet metal is all different between 56 and 57, some guys don't notice this.
That's good because I have 56 hinges and 56 front clip. I will die-grind the holes in the hinges to make them longer. Good to know that 57 outer sheet metal is different from 56. I thought it was the same.
An easy way to tell a 55 - 57 cab from a 58 - 59 is to look at the center of the fresh air plenum, right at the base of the windshield. This would be directly under the center of the fresh air grill. The 55- 57 cabs will be basically flat, and slopes forward and to the outside of the plenum. The 58 - 59 cabs will have a hump right under the center of the air intake grill. This is the reason that the wiper motors do not interchange.
I have had several 55 & 56 trucks, I didn't know the difference between 55/56 & 57. I thought I knew it all. lol I would like to know the difference in the front fenders if anyone has pictures to post here. Thank You Squirrel! and others as well to help me be aware of all these differences!
The battery trays are different too but mount the same. 58/59's sit the battery down lower with the same basic design. I have one in my '57 and like it lower.
The front sheet metal on a 57 is different so the new grille will fit. The upper and lower valences are different, and the fenders have flat spots and bolt holes, all this is because the grille opening needed to change to work with the bigger 57 grille, which overlaps the grille opening. Also the 57 has the hood "rockets".
oh yeah...another fun tidbit about swapping front sheet metal...the 58-59 frame is a couple inches longer to accommodate the different sheet metal.
Here is how I solved the hinge problem. I drilled a new hole just above the bottom mounting hole in the firewall. Then I welded a square nut on the inside of the firewall sitting on top of the existing lower nut. Now the 58-59 cab will accept the 55-57 hinges.
I did that to my 57 suburban, when I planned to put a 59 front clip on it. The nuts are still there, even though they are not used with the 57 hinges that are on it now.
all the important differences have been covered, first thing i check is front bumper fitment and then the hood hinge mounting to see if the cab has been changed. forgot about the divot for the wipers.
Mine has what looks to be the correct distance from bumper to fenders and other front sheetmetal. I remember looking at a 55 once that had too much space there and I wondered what was up. He probably had the wrong frame under his. Do you know what the frame length difference is between the two?
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