I bought a new (Ebay) motor for my '85 F150's wipers and the post on which you mount both linkage arms is too short. Grr! Sending it back.
I can't seem to locate one with the post visible enough to know it will fit, and mine was butchered by a previous owner and lacks the part that bolts on to the motor to drive the linkage.
Am I looking at going to a dealership parts department...where they grab your wallet and say "cough"!

 

I went to my local pull-a-part truck wrecking yard and got a wiper motor from my vintage Ford. Even if the motor is shot, I could transplant the longer shafted arm onto the new motor. Thank heaven for wrecking yards!

 

I had the same issue when I picked up a new wiper motor for my 85 from autozone. luckily I still had the arm for the old one. it took some filing of the opening on the arm to get it to accept the old post but I'd recommend hitting a junkyard and finding an old motor to salvage the post.

 

Exactly! I also had to file the hole a tad larger for the right fit.
Makes me wonder why these motors are made with shafts that aren't the right size? Like you only need one wiper?