Damper Rod Question .... 1978 390WR

[grouty]

I have acquired two new (ish) damper rods for the forks on my 78 390 Auto build as I had one damaged one.
My question is that I was going to use just one to replace the damaged one. I measured the new ones today, and found they are slightly different.

The original 390WR ones are 271mm long, the new ones are 274mm long.

The originals have 4 oil holes. Three down one side and one at 180 deg opposite the middle hole.
These holes start at 6.47mm dia at the top, middle is 6mm dia, and the lower one is 5.5mm dia. The one on the other side is 5.95mm dia.

The new rods only have the three down one side. All at 5.98mm dia.

What were these new ones fitted to ? A CR or WR. How much difference in damping will there be ?

I guess I am going to have to use the matching pair, and I can enlarge the top hole to 6.5mm and drill the one on the opposite side. But I cannot make the lower hole smaller.

These all have the M8 thread in the bottom. I do have one odd one in my spares box that has an M10 in the bottom.

Any help would be nice 

[PEZBerq]

Grouty,  it doesn't matter if they are the not the same as before since you need to set them up to suit your riding style and weight anyway - spring rate, oil weight, oil height.

You also have the option of fitting gold valves where you drill out the damping holes anyway so it doesn't make any difference what rods you start with. I fitted gold valves to my 78 auto. Worked much better than original.