The Stovebolt Site Forums The Shop Area Driveline Trailing arms

What is the difference in the trailing arms for 1960-1966 and 1967-1973? One parts vendor has different pat numbers and another does not. And while I am asking, what difference if any is there between 1/2 ton and 3/4 ton. I have a 67 with both arms collapsed(rust has won this time) and have found a 63 as a project for a new driver. The 63 is a 1/2 ton and the 67 is a 3/4 ton. If there is no real reason not to I will use the 63 as a pattern to replace the failed arms in the 67.If there is a difference, then I may have to keep looking for replacements. The things are rather spendy and that is making it a possible "project" goal. Thanks in advance. Steve.

My observation may not be helpful, but here goes.
I recently bought a 1961 parts truck with the x-frame. Someone tried to fit a 1965-72 12 bolt rear and trailing arms onto the x-frame. It’s very clear to me that the geometry is wrong. The trailing arms contact the X part of the frame with any weight on the frame.
I suspect that the mounting brackets on the rear axle are closer to the centerline in the 1963-1972 geometry, but I am not sure. Perhaps the brackets that mount the trailing arms to the frame or closer together for an x-frame chassis.
I do know this, the trailing arms for a long bed are the same as the trailing arms for a short bed.

Lugnutz: Thanks. That is in fact helpful. Sorry for the delay. Life gets in the way. Time is the one thing in short supply. If 63 is the chassis change year, then all is good. Measure, cut, shape and..you get it. PROJECT time. This could be fun.
Steve.

I have not dealt with anything but 1965 3/4 tons. However, I bought some LMC trailing arms years ago. I'd planned on replacing the arms, and had some u-bolts made up to match the existing ones. I was going to take it to a local shop to have them do the work so I didn't have to deal with the old bolts holding them to the frame. Glad I checked everything first. The 3/4 ton arms seem to have a wider bolt pattern, so to speak, for the u-bolts. The u-bolts would not go through the C10 arms from LMC. So they sit unused. And LMC doesn't have C20 arms available the last time I checked.