Finishing up the 68 Formula S I'm doing and I think I might have mixed up the strut rods. I had one of the original strut rods that was bent so I grabbed one out of "stock" and I go to put the new nuts on today and the first nut I put on just spins, wont tighten up. I think I must have gotten B-body nuts. So I look around, no nuts to be found, No biggy I'll just grab some at the store to hold me till I get the right ones. Then I got to thinking, is there a difference between A and B strut rod nuts???? After a little reading on here through the search function I might have figured out my issue, I might have a later A body strut rod on one side and the original 68 on the other. This got me questioning things I thought I knew. So here are the questions:

Is there a difference between A and B strut rods?

Is there a difference between A and B strut rod nuts?

Is there variations is strut rods and nuts for different years?

Is there a strut rod application chart with dimensions and thread size?

Thanks in advance, Kevin

I know there are different A body ones. We ran into that changing a bent one on a '70 Dart. Tried one from a '76 Duster and they were different.

Early has fine threads on the bushing end, late is coarse. Not sure about a diameter difference. I've got several of each on the shelf.

I also read something about the roll pin hole is closer to the end on the later ones. I'll double check the threads and holes tomorrow.

Firm Feel lists the SAME part number for the A-B-E body cars. I was curious about this and when I saw they thought that they were the same, that was good enough for me.

Bushing shows to be a different part number for A and B/E but that could be due to a K member differences.

70-71 parts manual shows 4 different strut rods and bushings (except Imperial uses the B/E bushing).
A body
B/E body
C body
Imperial.

Retainers (cup washers) and nuts are two numbers.

A body
Everything else

looking at the 65 parts book same strut rod part number as the 70/71 parts manual but the 74 parts manual shows a new number (only looked at A body)

From the factory A body rods are smaller diameter than B/E body ones. Also 67-72 are different than 73-76 for A body. Not sure about 62-66 but think they are different too.

Don't know if this helps, but I have a one owner '69 Formula S built November 1968..

My strut rods are threaded on both ends 9/16"-18 threads per inch. The K-frame bushing end nuts are cadmium or zinc plated, 1" across flats, 0.63" thick. See photo. Note that the 1" across flats is unusual and makes the nuts look fatter than normal.

The control arm end is a hex lock nut with the same 9/16-18 threads but 3/4" across flats, 0.58" thick and phosphated. Sorry, no photo, but I might take one if you ask. This 3/4" across flats is more normal looking for a 9/16" nut.

The only other 9/16"-18 nuts on the entire car are three hex tri-slots 0.63" thick on the lower ball joints and the idler arm, and six skinny 0.32" thick hex nuts on the quarter window mechanisms. The upper shock mount hex lock nuts inside the trunk are 9/16-20. The frame side ball stud for the clutch torque tube is 9/16-12. There are no other 9/16" nuts on the car other than these mentioned.

These photos are a 1968 Formula S from Carlisle three years ago.

Thanks Kent, pretty informative. What I found today was that the B rod is noticeably thicker than the A rod and about an inch or so longer. The B takes a 5/8 course at the bushing end with a 15/16 nut and 9/16 fine on the control arm end with a 3/4 nut. The A on all my 69s and the 68 I'm building are 9/16 fine on the bushing end with a 1 inch nut and 9/16 on the control arm end with a 3/4 nut. I originally thought I must have put a late A rod in due to the course nut but it just dawned on me that I had difficulty getting the torsion bar in deep enough on that side and since I really don't have any later A parts and the roll pin hole is deep like the original, I'm betting I picked up a B rod without realizing it. Anyway I located the right one and will swap them out in a few days and then measure the one I remove against a known B.

I understand that the later A rods went to course threads on the bushing end but a question for someone to knows; what diameter is the thread on a later A?

Just as a note in case anyone searches this for info, I read in my search that the later A rods have the roll pin hole closer to the end of the rod, maybe 1/2 inch from the end and the earlier A has the hole about an inch from the end.

Thanks for the info folks it has been helpful.