I am in the middle of installing a '79 Monte Carlo clip onto the front of what I thought was a '55-'57 3100 bare frame. The guy I bought if from said it was a '56 frame. I found out later that the frame turned out to be a '58 frame, and the overall length of the '58 frame was a little over 2" longer than the dimension of a '56 frame. Once I researched into my '55-59 assembly manual, I was able to locate the '55-57 frame specs, but didn't find any '58-59 frame dimensions. The '55-57 frame has an overall length of 178". This is shown on section 2 page 24 of the assembly manual. My '58 frame, before I cut it was 180-1/4" overall. I do know that the wheelbase is 114", common to all '55-59 Task Force trucks. I have gathered info on various forums that state the extra length of the frame siderails is at the very front of the frame, and everything in between is exactly the same. I have recently found out that the core support location is also different. The '55-57 trucks have a different core support than the '58-59 trucks, and I knew that. What I didn't know was that the '58 core support brackets that are riveted on the top of the frame rails are located 1" further towards the front of the truck. I initially made a jig to locate the front core support of the truck, so that after I spliced the Monte clip onto the frame, I could also attach the core support and front bumper frame ends off of the original frame using my jig. This jig bolts to the frame, and also bolts into the front core support mounts themselves. I have vertified that the '58-59 core support center line is 1" further towards the front of the truck, than the '55-57 frames. After measuring everything a bunch of times before I cut the original frame to graft on my Monte clip, I found this out. The factory assembly manual has the frame specs in section 2, sheet 24. A bunch of the dimensions refernce the "Front of Dash" line. The center of the "Radiator Bracket" for the '55-57 is 33.76" from the Front of Dash reference line. My jig that I made BEFORE I found out that I had a '58-59 frame located the front core support exactly 34-3/4" from the Front of Dash line. Pretty much 1" further forward than the '55-57 frame spec. So I adjusted my jig back 1" to then get everything back into alignment. I am wanting to document this to hopefully verify that the dimensions are different on the core support bracket locations from the '55-57 and '58-59 trucks. I know now that the frames are not exactly the same, yet with a few modifications, they can be interchanged. One other note I have found once I started researching frames. The radiator support brackets riveted on the frames have two different styles. One bracket has a cage nut and the bolt goes down through the core support and into the frame bracket. It allows for maybe 1/4" adjustment. The other style has a "T" slot and uses a carriage bolt setup. This design allows the head of the carriage bolt to slide into the slot on the frame bracket for adjustment, with the bolt facing up and a nut on top to secure the core support. I don't know what year diffences there are on these types of core support brackets. If anyone has any info, I would like to know. Thanks!
Last edited by Oleblue55; 12/31/2008 3:28 AM.
