I'm putting a new idler arm on my 72 Dart, having a hard time getting it in with washer, & do you got to have two washers?... One I took off had 2, the Moog one I'm putting on, come with only one washer.

are you able to mix and match washer(s) to get it in there snug? I would compare the "height" where it locates the center link from the new one to the old. not sure how critical a slight height change is but I would check it.

If only one fits use one.
When you tighten the bolt be sure all vertical movement is gone.
There should be a steel sleeve in the center and when you tighten it down it will move left or right freely with no play up and down.

Got it in with one of the old wisher on bottom, new wisher was a hire too thick, but new idler may rub exhaust now, it was all ready close, so looks like I,m going haft to get it bent right!

how are you planning to get that done?

Douse Idler arm haft to be 100% even with pitman arm?... Because the Idler is just up a little more!

when you compare the two idlers how much difference is there?

Take the washer from the bottom and re-install it on the top. This will drop the arm a little.

After I test drove it, it drop down some, its close to even now, but not 100% even, but close!.. So may be ok I hope, It was same as my old one side by side, my old one had two wishers, could only put one on bottom, like to never got it with just that one!
Institutions sead put washer on bottom & one on top if new one come with 2, it only come with one, looks like to me you need one bottom for it to move on, so I think you would haft to keep one on bottom!